A computer model for input/output analysis in dynamic management information systems.

Transcription

1 Lehigh University Lehigh Preserve Theses and Dissertatins A cmputer mdel fr input/utput analysis in dynamic management infrmatin systems. Pefter W. Hartranft Fllw this and additinal wrks at: Part f the Industrial Engineering Cmmns Recmmended Citatin Hartranft, Pefter W., "A cmputer mdel fr input/utput analysis in dynamic management infrmatin systems." (1979). Theses and Dissertatins. Paper This Thesis is brught t yu fr free and pen access by Lehigh Preserve. It has been accepted fr inclusin in Theses and Dissertatins by an authrized administratr f Lehigh Preserve. Fr mre infrmatin, please cntact preserve@lehigh.edu.

2 A COMPUTER MODEL FOR INPUT/OUTPUT ANALYSIS IN DYNAMIC MANAGEMENT INFORMATION SYSTEMS by Pefter W. Hartranft A Thesis Presented t the Graduate Cmmittee f Lehigh University in Candidacy fr the Degree f Master f Science, in Industrial Engineering Lehigh University r

3 PrQuest Number: EP76165 All rights reserved INFORMATION TO ALL USERS The quality f this reprductin is dependent upn the quality f the cpy submitted. In the unlikely event that the authr did nt send a cmplete manuscript and there are missing pages, these will be nted. Als, if material had t be remved, a nte will indicate the deletin. uest PrQuest EP76165 Published by PrQuest LLC (2015). Cpyright f the Dissertatin is held by the Authr. All rights reserved. This wrk is prtected against unauthrized cpying under Title 17, United States Cde Micrfrm Editin PrQuest LLC. PrQuest LLC. 789 East Eisenhwer Parkway P.O. Bx 1346 Ann Arbr, Ml

4 j- This thesis is accepted and apprved in partial fulfillment f the requirements fr the degree f Master f Science. y/v/7+ (date) Prfessr in Charge Chairman f Department ii

5 Acknwledgements /> The authr wishes t thank the fllwing persns in cnnectin with t$iis thesis : Dr. Ben L. Wechsler fr his advice,assistance, and cuntless review cmments. Mr. and Mrs. J. William Hartranft, the authr's parents, fr their guidance and encuragement, and fr prviding me the pprtunity t gain my cllege educatin. ik

6 3 Table f Cntents Page Abstract 1 Chapter I. Intrductin A. Backgrund B. Statement f the Prblem C. Objective.., D. Apprach 11 Chapter II. Develpment f Algrithm A. Evaluatin f Pssible Mdificatins 13 B. Reverse Order Prcessing 13 C. Precedence Relatinships 15 y. Cmbinatin f Outputs 17 E. Vlume Assignment t Data Items.. 19 F. Incrpratin f Changes 20 G. Revisin f Step-by-Step Prcedure. 31 H. Guidelines fr Analysis f Results. 31 Chapter III. Develpment f Cmputer Mdel A. General Descriptin B. Instructins n Use f the Mdel 40 iv

7 Table f Cntents (cntinued) Chapter IV. Test Cases Page A. Validatin f the Mdel 43 B. Lehigh University Registratin System 48 C. A Prgram Evaluatin and Review System fr the Department f - Energy Chapter V. Cnclusins and Recmmendatins A. Cnclusins. 59 B. Areas fr Further Study 62 List f References 65 Appendix A. Mdified Step-by-Step Manual Prcedure fr Data Flw Algrithm 66 Appendix B. Lehigh University Registratin System Example Dcuments. 70 Appendix C. Dcumentatin f Cmputer Mdel 77 Appendix D. Lehigh University Registratin System Output Reprts Appendix E. SPERS System Output Reprts. 113 Vita \

8 List f Figures N Page Fig. 1. Initial Matrix 4 2. Matrix Fllwing Multiplicatin Initial Matrix fr a Dynamic System' "9 4. Example f an Event Netwrk Sectin f an i/o Matrix Flwchart f Student Registratin Prcess at Lehigh University A. Subsystem B. Subsystem C. Subsystem D. Subsystem Flwchart fr Mdified Manual Prcedure f Data Flw Algrithm Input/Output Relatinships fr a Hypthetical Management Infrmatin System SPERS General System Flwchart.. 54 vi

9 Abstract This thesis cncerns itself with the input/utput relatinships and data flw thrugh management infrmatin systems. A data flw algrithm develped by Jhn F. Wilsn and William A. Smith Jr. was analyzed and fund t- have sme limitatins in certain circumstances. It was discvered that this algrithm was nt designed t handle dynamic infrmatin systems, where feedback lps exist within the system. In rder t mdify the existing algrithm, several system analysis techniques were evaluated t determine hw applicable they were in a revised mdel frmulatin. This evaluatin prvided the fllwing results : 1. The Time Autmated Grid Technique is an infeasible system analysis technique fr analyzing the flw f data in an infrmatin system. 2. Precedence relatinships are a helpful design tl, t be used in an input/utput analysis, fr identifying an updated dcument as a part f an infrmatin feedback lp. A mdified manual prcedure fr analyzing the data flw in a dynamic management infrmatin system was prpsed that wuld cmpute the number f times a data item is made availible t a business functin.

10 This mdified algrithm subdivides the infrmatin system being analyzed int static subsystems which are snap shts taken at times which eliminate the feedback lps ccurring within, the system. In additin, a cmputer mdel was develped that autmatically cmputes the availabilities f the data items, as well as prduces a series f reprts t aid the analyst in investigating the flw f data thrugh an infrmatin system. This mdel was tested against three realistic applicatin cases and was fund t be successful in prducing the utput reprts fr all three cases.

11 Chapter I Intrductin A. Backgrund ( Althugh the cncept f a management infrmatin system has been arund fr many years, system analysis techniques used in the develpment f such systems have nt yet been cmpletely evlved. While significant prgress has been made in the area f mathematical mdeling and in the use f such analytical tls as matrices, decisin tables, flwcharts, and grid charts in designing MIS, we still have nt develped a cmplete understanding f their use in the analysis^f data and infrmatin flw. In 1962, Hmer designed an algrithm fr analyzing the number f times an input was made available t an utput. (1) In essence he used the grid chart technique t cmpute the number f pssible paths an input element culd travel thrugh a system befre being made available t an utput element. His mdel cncerned the input data cllected, the flw f data in the system, and the utility and relevance f the data. In frmulating the mdel, he als used matrix algebra techniques which give the mdel the imprtant characteristic that it can be mathematically manipulated. In rder t use it, identificatin is required 3

12 ? f the varius data elements (inputs), reprts (inputs r utputs), and business and decisin- making functins (utputs). Having identified these cmpnents, matrices can be established fr each reprt level and the input and utput relatinships can be shwn. In Hmer's algrithm, an initial single matrix must be established frm the reprt level matrices in which the rws are the input data (d), and all the reprts (R) that are in the system. The clumns f the matrix are all the (R) reprts and the business functins (B). The matrix must be filled in with l's where a data input appears n a reprt, r where a reprt is used t prduce anther reprt r business functin. All ther remaining cells f the matrix shuld be filled in with O's, except the cells which are frmed by the intersectin f identical rws and clumns (reprts), which shuld have a -1 inserted. This leaves the matrix in the frm f Fig. 1, where t-i) is the negative identity matrix. R B d X 0 R -I Y Fig. 1. Initial Matrix

13 Hmer further ges n t shw that the elementary matrix peratin f adding a multiple f the clumns cntaining a -1 t the clumns f Y such that Y becmes zer, is equivalent t multiplying X times Y yielding the matrix in Fig. 2. R. B d X XY R -I 0 Fig. 2. Matrix Fllwing Multiplicatin This manipulatin creates a slutin area in the set f cells whse crrespnding rws and clumns d nt cntain -l»s. In the abve figure this crrespnds t the upper right submatrix (XY). Accrding t the algrithm, this resulting submatrix will indicate the number f times each data input (d) is made available t each business functin (B). While this algrithm was an imprvement n prir methds, Wilsn and Smith recgnized that it had several shrtcmings. (2) Upn analyzing Hmer's mdel, they shwed that it assumes input data frm each surce t be independently transferred t each subsequent reprt. This prduces the cmputatin f the number f pssible paths each input culd travel, rather than the number f times a piece f data is 5

14 actually available t business r decisin-making activities. Fr example, suppse that reprt Rl has data items dl, d2, and d3 recrded n it, and Rl is used t prepare reprts R2 and R3» Finally, R3 is used fr business functin Bl. The resultant matrix, in Hmer's algrithm, wuld shw that items dl, d2, and d3 are made available t Bl. Hwever, if in preparing reprt R3, d2 is nt transferred t R3 frm Rl, the resultant upper right submatrix wuld describe a pssible path but nt the actual data transfer. Anther questinable assumptin that Wilsn and Smith fund in Hmer's wrk was that multiple recrding f identical data n a reprt ccurs. This makes the preparatin f reprts similar t a parts assembly prcess in a manufacturing envirnment. They interpreted the data flw netwrk described by Hmer t represent a parts assembly prcess where the d's are input parts, R's are subassemblies, and the B's are final assemblies. It seenied highly unlikely t Wilsn and Smith that a data prcessing system wuld use the data mre than nce in preparing a specific reprt, even thugh the same data may be avail ble frm several surces. As a result f their analysis, Wilsn and Smith extended Hmer's wrk in 1968 and prduced a better 6

15 data flw algrithm that determined the realistic number f times each data inpjat is made available t each business functin>^ They realistically assume that multiple recrding f identical data des nt ccur when a data element (d) is available frm mre than ne surce. In accrdance with.this assumptin, the- revised algrithm rewrites the upper left submatrix as a Blean matrix during every step f the matrix sweeping ut prcess. In ther wrds, after the matrix peratin f adding multiples f the rws and clumns cntaining -l's such that the lwer right submatrix becmes zer, all the nn-zer entries in the upper left submatrix are cnverted t l's. By rewriting the submatrix as a Blean matrix, nly thse data items which are actually recrded n each reprt are shwn. Then, t determine the number f times each data item is made available t each business functin, the next t last reprt level is multiplied by the last level a matrix. The last level matrix cnsists nly f reprts (R) as inputs and business functins (B) as utputs. Upn cmparing the number f paths frm the matrix in Hmer's mdel with the number f times available frm Wilsn and Smith's slutin matrix, each data item/ business functin ^cell f the latter is equal t r 7

16 less than the frmer. Wilsn and Smith state that the maximum number f times each data item culd be available t each business functin is equal t the number f reprts ging t each functin. By changing Hmer's algrithm t reflect the mdificatins previusly described, Wilsn and Smith develped a much mre wrkable and realistic mdel. Hwever, in applying this algrithm t an input/utput analysis fr an infrmatin system design, it sn became apparent that it t has sme limitatins in sme circumstances. It appears that the algrithm is nt designed t handle a dynamic situatin, ne where feedback lps exist within' the system. This type f a dynamic situatin will ccur when a reprt is prduced initially and then is later updated. The reprt will nt be a "nce and dne n item, rather it will be changed frm its riginal frm and cntents. The prblem that this situatin creates is that a reprt which was prduced frm a different reprt culd later be an input t an updated versin f the same reprt. An example f a dynamic system and what it des t the matrix in Wilsn and Smith*s algrithm is shwn in Fig. 3 n the fllwing page. In this case, reprt R2 is prduced frm Rl and reprt R3 is in turn S

17 Rl R2 R3 R4 -, Rl R2 R3 R4 B X 0 Rl R2 R3 R ^ Y Fig. 3. Initial Matrix fr a Dynamic System

18 prduced frm R2. Next, R3 is the input that prduces R4. <- Hwever R4 is then used t prduce an updated versin f reprt R2, creating a feedback lp. In an actual applicatin, all the data items that make up the lwer reprt levels wuld als be included, but they have been left ut f the example t keep the matrix simple. As can be seen, a 1 appears belw the -1 diagnal in the lwer left submatrix. N matter what matrix peratins are perfrmed the submatrix can nt be manipulated int frming a negative identity matrix, which is necessary fr the data flw algrithm t wrk. This will be the case s lng as any nn-zer entry exists belw the -1 diagnal, and it can be shwn that this will happen whenever a feedback lp ccurs in the infrmatin system being analyzed. Sa B. Statement f the Prblem r ~ The Wilsn and Smith mdel is successful in dealing With a static system. In practice, there are infrmatin systems that frequently cntain feedback lps in the flw f data frm ne bundary f the system t the ther. Thus, we d nt have an effective, algrithm (technique) fr analyzing input/utput in a dynamic situatin. 10

19 C. Objective The bjective f this thesis is t extend the Wilsn/Smith Data Flw Algrithm s that it prvides a means fr analyzing data flws in a dynamic infrmatin system. A cmputer mdel will be designed t perfrm the basic steps f the mdified algrithm and prduce a series f reprts summarizing the results, ( D. Apprach The first step tward achieving the bjective will be the revisin f the manual prcedures fr analyzing the system and manipulating the i/o matrices. This will invlve.evaluating the pssible techniques which might aid in the mdificatin and incrprating acceptable changes in the Wilsn/Smith mdel. The manual step-by-step prcedure fr using the data flw algrithm will then be revised and a set f guidelines will be develped t analyze the utputs f the mdel. After a cncise manual prcess is prvided fr evaluating the input/utput flw in an infrmatin system, step tw will be the develpment f the cmputer mdel. This wrk will start with general flw charts and input/utput frm design. Subsequently, a detail flwchart will be develped frm which the actual cde f the mdel will be written. The 11

20 cmputerized mdel will be tested and debugged by using three test cases f actual existing systems. The step-by-step prcedure fr using the cmputer mdel will be utlined, and a discussin f the results f the three test cases will be prepared. 12

21 Chapter II Develpment f Algrithm A. Evaluatin f Pssible Mdificatins Befre any changes are made t the Wilsn/Smith algrithm, t make it useful in a dynamic situatin, varius alternatives f system analysis techniques that might be applicable will be investigated. The fllwing fur techniques will be evaluated fr their use in the mdificatin : reverse rder prcessing (utputs leading t inputs), used in the TAG - Time Autmated ' Grid System - precedence relatinships - "deadweight" transfer (cmbining utputs) - vlume assignment t data items B. Reverse Order Prcessing The first f these techniques invlves the basic principle behind the use f the TAG system. This principle is the feeding f data, relating t the ut* puts f a system, int TAG and allwing TAG t prduce the inputs that will be necessary and the pints in time these inputs will be needed. Use f TAG begins with transcriptin f the system^ utput data requirements n an Input-Output 13

22 Analysis Frm. Once the utput data requirements have been fed int the TAG system, TAG wrks backwards frm the utput t determine the necessary inputs. When bth inputs and utputs have been defined by TAG, the next iteratin f the prgram prduces file f'rmat descriptins. File cntents are based upn time, the time at which data elements enter the system and the time at which they are required t prduce utput. T TAG, it is the elapsed time between these tw mments that creates the need fr files. The files that TAG defines indicate what data must be available t enable the system t functin. The user btains an verview f the system, shwing what inputs are necessary. Knwing the availability f data elements makes it pssible fr the system planner t determine whether the utputs desired are quickly and easily btained, and thus ecnmically justified. This type f technique is particularly well suited t the design f systems that are n a very large scale, where numerus utputs are required. The mst beneficial results that TAG prduces describe the minimum requirements fr the data base. (3) The purpse f the input/utput algrithm is t shw which inputs are made available t which utputs in an existing system, nt t minimize the number f 14

23 initial inputs (unless they are nt a useful part f the system). The algrithm will attempt t shw which reprts culd be eliminated r cmbined with ther reprts in rder t prduce the same quality utput" functins. In using the methd f TAG, intermediate reprts (that are necessary requirements f the system) are lst in the quest t prduce a minimum data base. This happens using the reverse rder apprach since it fails t cnsider the actual flw f data thrughut the entire system. Thus, althugh the Time Autmated Grid technique is an excellent tl fr the develpment f a management infrmatin system, its applicatin t the input/ utput analysis fr an existing system is nt entirely feasible. Because the TAG system des nt analyze the data flw f a system, it has been decided nt t use the apprach f starting with the desired utputs and deriving the prper number f inputs. C. Precedence Relatinships The next system analysis technique which will be investigated is the use f precedence relatinships fr the case f a reprt being updated in the system during prcessing. (4) Precedence relatinships find 15

24 sme f their mst useful applicatins in PERT r CPM charts. These charts are netwrks f events in which a set f events can be shwn as being necessary t be cmpleted befre anther event can be started. Fr example in Fig. 4, if events A, B, C must be cmpleted befre event D may be started it will be shwn as fllws : Fig. 4. Example f an Event Netwrk In this case, it is said that events A, B, C cnstitute the precedence set fr event D. It shuld be nted that precedence relatinships can be applied t different entities ther than events. Fr the purpses f the input/utput analysis, precedence relatinships will exist between any cmbinatin f the data elements, reprts, r business functins. As anther example f the way precedence relatinships wrk, cnsider the case where a reprt is used as an input t an updated versin f the same reprt. That is, assume reprt X and data item M are used t prduce an updated versin f reprt X. In this case, 16

25 X and M are the precedence set fr reprt X», where the prime is used t dente an updated versin f a reprt. Fr this example, it is bvius that any reprt is a precedent fr the updated versin f the same reprt. This cncept f precedence relatinships will be very useful in the mdificatin f the I/O algrithm t handle dynamic situatins. It mainly will be an aid t distinguish when a reprt r business functin has been updated as a part f a feedback lp within the system. D. Cmbinatin f Outputs The third technique, t be evaluated fr its use in mdifying the algrithm is the cmbinatin f tw r mre utputs t yield a single utput cntaining the saigp infrmatin. This cncept wuld be applied in the instance when tw reprts r business functins appear t be very similar, that is, cntain many f the same inputs r data items. It is used t reduce the number f utputs (r intermediate reprts) and cnslidate the elementary reprts int a cnglmerate f larger reprts r functins. (4) In general, the number f reprts prduced within the system wuld have t be kept at a reasnable limit 17

26 fr cst reasns. Hwever, cmbining certain reprts might cause excessive data transprt by causing data t be input t a prcess where it is nt ging t be used. This is a pint that the analyst must evaluate carefully befre making a decisin t cmbine utputs. sas an illustratin f what might happen, cnsider the case in Fig. 5 f cmbining reprts A and B tgether : ' Rl R2 R3 R4 R5 R6 A 0 1 r B Fig. 5. Sectin f an i/ Matrix It can be seen that in tw f the fur transprts f - A we will have t transprt B as a deadweight. Likewise in ne f the three transprts f B we will have A as a deadweight. Thus, a ttal f 2 B's and 1 A will be transprted unnecessarily. By gruping reprt 4 with reprt 3 and reprt 5 with reprt 6 tw f these deadweight transfers are eliminated. One prblem with this type f analysis is that it tends t make the system excessively cmplicated, especially as it grws larger. Hwever it still remains quite easy t calculate the ttal extra transprt f data if tw reprts are cmbined int ne. 16

27 Thus, this methd may be valuable in helping the analyst spt where he might begin lking fr cnslidatin within the system with which he is wrking. With the aid f a high speed cmputer t perfrm this type f calculatin, the analysis f carrying deadweights becmes much mre feasible. '?-V, E. Vlume Assignment t Data Items Anther system analysis technique evaluated is vlume assignment t data items. In this applicatin the relative vlume f a data element r recrd is indicated s that it will be pssible t see hw much is saved by cmbining specific items. In the case f an input/utput analysis, the vlumes wuld be characters, bits, lines r whatever is a cnvenient unit t measure the size f the data items. Thus, if an analyst has determined that data element (a) is made availible t reprt D three times and reprt E twice, and we knw that the vlume f element (a) is ten characters; the ttal transprt vlume f data element (a) wuld be (3 + 2)10-50 units. Use f this technique wuld enable the analyst t quantify hw much transprting wuld be reduced (r increased) in mdifying the paths f the data. Hwever, fr this t be pssible a significant amunt 19

28 f memry must be available in the cmputer fr the cmputatins required and the results prduced. In the general case, ne wuld have t test all the different cmbinatins that culd ccur, and it is fr this reasn that the assignment f vlumes t all data items is nt practical. In spite f this, the technique can still be used in the analysis f an infrmatin system. After a preliminary analysis, the analyst shuld have an idea f which data items might be cmbined t increase the efficiency f the system. It is at this pint that vlumes culd be assigned t nly thse items that the analyst has identified, and frm there the necessary cmputatins culd be made t yield a quantified slutin. In this way strage space and csts can be kept at a reasnable level. F. Incrpratin f Changes The mst imprtant mdificatijyi that needs t be made t the Wilsn/Smith mdel des nt invlve the actual manipulatin f the algrithm, but rather the analysis f the existing system prir t setting up the matrices. This mdificatin is necessary t insure a successful analysis f a dynamic situatin. In rder t use the Input/Output algrithm fr 20

29 a sequential dynamic system, it is necessary t break dwn the system int subsystems. The subsystems are snap shts f the system taken at times which eliminate feedback lps that ccur within the system. In rder t demnstrate hw the existing system shuld be segmented int subsystems, an example will be used f an actual infrmatin system that is used in the student registratin prcess at Lehigh University. A general diagram f the prcess is shwn in Fig* 6, with the numbers used as an aid in fllwing the flw f data thrugh the entire system. Appendix B cntains example cpies f sme f the dcuments used in the registratin system. A descriptin f the verall prcess is included in the fllwing paragraphs. The first dcument (see Appendix B) that is used in the registratin system has been termed the "Unnamed Frm" fr bvius reasns. It is prepared by each department in the University that plans t ffer curses during the upcming semester, and includes data elements such as curse number, curse name, credits, hurs per week, instructr, etc. This frm is used alng with the experience and intuitin f the registrar t prduce a master assignment bard kept in the registratin ffice. It is frm this bard that the registrar can 21

30 22

31 develp a tentative schedule f classes, which the student may use alng with whatever thught prcess is required t fill ut the first half f the pre- registratin ticket. r The registrar then cmpiles and tabulates a reprt shwing the resulting statistics f all the preregistratin tickets. Frm these statistics, which give a gd indicatin f the preferences the students have, the registrar updates his master assignment bard t include such changes as adding an additinal sectin fr a curse, r drpping a curse frm thse riginal- ly ffered. The registrar may nw use his bard t prduce the final schedule f classes t be ffered in the upcming semester. The registratin ticket (see Appendix B) is then cmpleted using the data frm the first half cmbined with the final schedule f classes. The next step in the registratin system is the use f a cmputer prgram t cmpile and create a registratin file that ' is kept n magnetic tape. It is frm this file that an autmated system is used t prduce the class lists and student rsters., which are distributed thrughut the University t the apprpriate students and instruc- trs. In the next step, the student lks ver his 23..

32 rster f curses t decide if he wants t add r drp a curse. If Tie decides that he des, he must fill ut an add/drp slip. This slip is then pr- cessed and updates are made t his curse rster and als t the registratin f>ile. Upn the updating f the registratin file, a cmputer prgram is used t prduce revised versins f the class lists. Half way thrugh the semester, the student still has the pprtunity t drp certain curses, fr valid reasns, but he may nt add any mre curses. If a student wishes t drp a curse he must fill ut a petitin and have it signed by the instructr, dean, etc. Upn the successful cmpletin f this prcess, updates are again made t the student's rster and the registratin file, and a mem is sent t the in- \ structr f the curse the student drpped. This cmpletes the prcess f registering fr curses at Lehigh University. Frm this descriptin, it can be seen that the registratin system definitly perates in a dynamic envirnment. Numerus reprts are updated thrughut the prcess, and sme are updated mre than nce. Thus, t perfrm an accurate input/utput analysis f this system, it will be necessary t reduce it t static subsystems. 24

33 -1 ^ A prcedure fr reducing the system t static subsystems fllws. Whenever the flw f data lps back t be input int a reprt that already exists, a feedback lp ccurs, and this updated reprt shuld be the first dcument prduced in the next subsystem. Fr example, in the registratin system, the first feedback ccurs in step 5 in Fig. 6 when the registrar uses the registratin statistics t prduce an update t his master bard. Thus, the registratin statistics shuld be the last reprt prduced in the first subsystem, and the updated master bard shuld be the first reprt prduced in the secnd subsystem. Fig. 7A thrugh 7D shw hw the registratin system at Lehigh University shuld be segmented int static subsystems prir t being analyzed by a data flw algrithm. The slid lines represent the sectin f the verall system that is t be included in that particular snap sht r subsystem. In the example presented here, there are a ttal f fur (4) subsystems, and fr each f these a separate input/ utput matrix manipulatin must be carried ut when perfrming the algrithm manually. The secnd majr change in the algrithm includes hw the separate subsystem matrices are set up. Althugh, by definitin, a subsystem is itself a system, 25

34 en _3T EH CO CO CO M a** i / EH SB «W W Q EH D CO EH O CO «I I \ \ A-\-' EHO A ZH Ov *T W EH & x^.r± w EH WO COP. EH / I O EH D : OEH 9 ss \ \ \ N V \ «*x V I J~y I \ \ / W \ V N H.. rh P< Q 04 CO CO «5 «q En w S CO EH < H CO O O < pq 8P «3, / / / I O t W CO i^ i-l w rtj!d CO!3 Q CO H W < O CJ CO I I A t A ,EH *w in 2 EH EH W CO «H CJ O H a P 01 ts CO O CO H <n 26

35 » g- EH» OU \ CLASS LIST A OEH T, en L. 1- _ / en tf S rt p EH w 5 WH<! H en a < CQ 8 S VOj PM O W w\ J.J W \ 2 :D en \!Z Q t 1 H W 3 PH K u a i ia 8"! Q H W En EH W 2 EH KJ EH W Pi CO «>J H CJ O O H S H in cv p CO >» CO JO CO fa CN T 27

36 fr* 1 z a w w \ Q EH \ D CO " EH O CO «EH i EH O «EH CO 55 A EH CO H O I I -.' I I VO, / / I i< H W CO ' CM', 'Q H 1 A w EH I-,EH rt! J W rf EH' II-P EH Wl Pj t tti S H CJ ' O H> vleu*! in -t- EHH 1 SEH * CO \ EH H \ CO EH M< O EH W CO *. i A I. O EH sal- P«EH i S P CO» CO CO H jr» O f»h 2d

37 «l \ * ^9 a: OH \ sen 1 gg J t 1 REGISTRA MASTER BOARD s p n 0) JO CO fao H \ O 29

38 it can nt be analyzed as being ttally islated frm the rest f the system in the input/utput analysis. Thus, when establishing ne f the matrices, a reprt that was prduced in a prir sybsystem must be brken ut int its separate data items. This is the nly way these individual data elements can be passed int the next subsystem frm utside and eventually shw up in the final result. This is imprtant because the result we are cncerned with is the number f times > a data item, nt a reprt, is made availible t a ^ business functin. In Fig. 7B f the registratin system example, the secnd matrix wuld nt have the registratin statistics appearing anywhere as a reprt. Instead, the data items that make up this reprt wuld be shwn n the matrix as inputs (rws) int the registrars master bard. This same prcedure wuld als be dne fr the first half f the preregistratin ticket since it was prduced in a prir subsystem as well. Once the analyst has segmented the existing system int its subsystems (if the system is dynamic), and has been careful t use the data items f reprts prduced in previus subsystems, the matrix manipula- tin fllws the same pattern f the existing algrithm 30

39 which is described in Appendix A. The remaining mdificatins invlve the interpretatin f the results f the matrix manipulatins and what t lk fr during the actual manipulatins. These additins t the algrithm fllw in this chapter under the sectin named Guidelines fr Analysis f Results. G. Revisin f Step-by-Step Prcedure In rder t make it easier t fllw the stepby-step prcedure fr using the manual data flw algrithm, a flwchart is shwn in Fig. 8. Indicated n the flwchart are the numbers f the steps that must be taken t carry ut the analysis. A cmplete listing f the steps is included in Appendix A. It is the intentin that the flwchart, alng with the listing f the steps f the algrithm, shuld suffice t allw a manual input/utput analysis f an infrmatin system. H. Guidelines fr Analysis f Results While the step-by-step matrix manipulatin prduces a realistic slutin space in the resultant matrix, anther value f the algrithm is the derivable infrmatin regarding the system that results. By reviewing 31

40 f START J FLOWCHART EXISTING SYSTEM (1) ANALYZE FLOWCHART (2) (Step Numbers are in Parenthesis) Dynamic Static IDENTIFY SUBSYSTEMS (3) MATRIX MANIPULATION FOR ENTIRE SYSTEM (6-ld) 1 r Fig. 8. Flwchart fr Mdified Manual Prcedure f Data Flw Algrithm 32

41 STEP (4) FOR FIRST SUBSYSTEM I MATRIX MANIPULATION FOR (6-17) SUBSYSTEM ANALYZE RESULTS ( END J READ RESULTS (IS) N STEPS (4,5) FOR NEXT SUBSYSTEM Fig. 8. Cntinued 33

42 the input/utput matrices, ne is able t spt flaws in the system and pssible areas fr imprvement t the system's efficiency. This type f infrmatin can prve t be as valuable, if nt mre s, as the data n the number f times data items are made available t business functins. The purpse f this sectin is t prvide a systematic prcedure fr analyzing the matrix(ces) that the algrithm prduces. The analyst shuld begin lking, befre the sweeping ut prcess, fr any areas where imprvements culd be made. The mst significant area fr imprvement that the initial matrices indicate is where verlap ccurs between tw r mre rws r clumns. Overlap ccurs between tw rws when a "l" appears in the same clumn in bth rws, (vice versa fr tw clumns). The amunt f verlap shuld nly be cnsidered meaningful when ne f the cmpnents is a cmplete subset f the ther, r at mst it misses being a cmplete subset by nly ne element. Having identified an verlap situatin between tw cmpnent0, the next step is t evaluate the cnsequences f cmbining them int ne cmpnent. There are tw different cases that culd ccur, the first being the simpler t analyze. This wuld be the case in which the tw cmpnents are f different types, 34

43 that is, ne a reprt and the ther a data item r business functin. Here the tw cmpnents shuld be cmbined int ne t imprve the system* efficiency, because bth cmpnents are serving the same functin. Keeping the tw cmpnents separate will add redundancy t the system. The secnd case is ne in which the tw cmpnents are bth reprts. This presents a slightly mre difficult situatin t analyze because the tw reprts will be represented as bth rws and clumns in the matrix. Thus, even thugh ne reprt might be a cmplete subset f the ther when they are used as utputs (bth reprts being prduced frm the same inputs), they culd be used as inputs int vastly different series f utputs. In this case, it is nt as bvius that cmbining the reprts will imprve the system's efficiency. The amunt f deadweight transfer must be analyzed t determine if the cmbinatin f reprts is desirable. Anther situatin which the initial matrix(ces) shuld be checked fr is a reprt appearing as nly an utput. This means that the reprt is nly a, system utput and it shuld be lked at in detail t see if it is serving the functin f the system being analyzed. Very ften this will nt be the case 35

44 and it might be pssible t remve the reprt frm the system. Gvernment reprts are usually gd candidates fr cmpnents that are an utgrwth f the system but are nt necessary fr prviding any decisin-making functins t management, but if regulatins require them they can nt be eliminated. Next, if there is any input (data item) that is used nly nce in the system, that is, the rw cntains nly ne "1" entry, it prbably shuld be used as an input parameter. This is mst applicable in an aut- mated infrmatin system where it becmes mre im- prtant t identify any specific items that must be input int the system. A great deal can be learned abut the system under analysis, and its cmpnents, prir t the setting up f the resultant matrix, simply by bserving the fl- lwing ccurences. 1. A rw r clumn cntaining n l's r -l f s - The crrespnding input r utput is utside the bunds f the system being analyzed. J 2. A rw cntaining nly a -1 - The cmpnent repre- sented by this rw is actually a system utput. 3. A clumn cntaining nly a -1 - The cmpnent represented by this clumn is actually a system input. 36

45 4. Bth a rw and clumn representing the same cmpnent cntain n l's - The cmpnent is nt a member f the system being analyzed. Finally, the analyst shuld bserve clsely and make nte f any instances f a cell in the upper left quadrant being cnverted t a Blean cell during the sweeping ut prcess. Whenever this happens the analyst shuld nte the rw and clumn that frm the cell. This indicates the spts where redundancy exists within the system and where specific data items might nt be required n reprts. 37

46 Chapter III Develpment f Cmputer Mdel A. General Descriptin A cmputer mdel was designed and tested that autmatically perfrmed the matrix manipulatins in the revised data flw algrithm. This mdel was written in FORTRAN IV since the language mre easily represents matrices than a business riented language such as COBOL. In additin, the CDC 64OO was utilized as the main frame cmputer n which the mdel was debugged in a batch perating mde. In cnjunctin with a batch peratin, input t the mdel was in the frm f data recrds keypunched. n cards which are then read ne card at a time. As the input cards are read by the mdel, the first utput reprt is prduced. This reprt is simply a reprductin f the input deck t serve as an ech check against pssible keypunch errrs by the user. A number line frm 1 t SO is included in the heading f the reprt t aid in lining up the clumns n the data cards. An example f this reprt as well as the ther reprts prduced by the mdel are included as a part f Appendix C. As the data recrds are input, they are stred 38 '.

47 in hlding arrays where they can be accessed later n by the mdel. At the cnclusin f the data input, these recrds are srted alphabetically by data element name and are utput t reprt 2, the Data Element Glssary. At this pint, the mdel runs thrugh an exhaustive search f the initial matrix fr pssible redundancy amng the data items and the reprts as they are being used as inputs in the system being analyzed. The criteria that is used t determine if a given pair f a data item and reprt qualifies as a redundant cmbinatin is if the individual elements that cmprise the pair have less than tw cells that are different in the initial matrix. In ther wrds, there can be at mst ne cell that is nt identical in the tw rws f the matrix that represent the tw data elements f the pair, fr the pair t qualify as being redundant. Any pair f data elements that meet this test are then utput t reprt 4 fr perusal by the user. Fllwing this search, the initial matrix is als scanned fr pssible input parameters (data items that are used as inputs nly nce), and fr pssible nnfunctining elements (reprts that are nly utputs in the system and nt inputs). If any such elements 39

48 are discvered by the mdel, the infrmatin pertaining t them is utput t reprt 5, the Data Element Fllwup Reprt. The remainder f the mdel is devted t perfrming the matrix manipulatins as perscribed in the algrithm, t eventually prduce a slutin matrix which will shw the number f times each data item is made availible t each business functin. This slutin matrix is the final result f the mdel and is utput t reprt 3 alng with the separate iteratins f the matrices, if desired by the user. B. Instructins n Use f the Mdel The fllwing step-by-step apprach shuld be emplyed when using the cmputer mdel fr analyzing the input/utput data flw f an infrmatin system. The accmpanying dcumentatin fr the mdel is included in Appendix C, and the actual surce cde is n file in the Industrial Engineering Department f Lehigh University. 1. Draw a flwchart and identify all the data items, reprts, and business functins f the existing system as utlined in steps 1 thrugh 5 f the manual prcedure in Appendix A. 40

49 2. Number cnsecutively all the data elements identi- fied in step 1 beginning with the data items, then reprts, and finally the business functins as they are used in the system, by fllwing the num- bered flw lines n the flwchart. 3. DATA DECK SETUP The first data card cntains tw cdes fr cntrlling the type f utput desired. The first cde is fr suppressing the utput f all the matrix iteratins and ges in card clumn 5 ( 0 fr sup- pressing the iteratins, and 1 fr printing the iteratins). The secnd cde is an ptin fr hav- ing nly the slutin space f the final matrix utput as ppsed t the entire slutin matrix and ges in card clumn 10 ( 0 fr printing nly the slutin space, and 1 fr printing the entire slutin matrix). The remainder f the data input cards take ne f tw different types : clumns 1-3 TYPE 1 data element number (the number previusly assigned in step 2) clumn 4 the digit 1 (input type number) clumns 5-46 data element name (descriptin f the data element) 41

50 clumns 47-4$ number f times the data element is used as an input in the * system being analyzed clumn 49 data element type ( D - data item R - reprt B - business functin) Each type 1 recrd is t be accmpanied by ne variable length type 2 recrd. The length f the type 2 recrd is determined by the number f times the data element is used as an input. If the data element is nt used as an input ( i.e. business functins) n type 2 recrd is required. clumns 1-3 TYPE 2 data element number (shuld match the data element number in the type 1 recrd) clumn 4 the digit 2 (input type number) clumns data element numbers fr each * time the element is used as an input In all cases where NUMBERS are t be keypunched n the cards they must be right-justified. The last data card shuld be a blank card, which is t be fllwed by an end-f-file card. 42

51 Chapter IV Test Cases A. Validatin f the Mdel (TEST CASE 1) The first test case run n the cmputer mdel served the purpse f validating the lgic and the accuracy f design f the mdel. In rder fr a cmprehensive test f the mdel t be accmplished, a test case r example was chsen that exhibits many different characteristics and peculiarities that are invlved in an input/utput analysis. The test case that was used fr this purpse was an adaptin f the same example f an infrmatin system used by Wilsn and Smith. (2) Thijs example, althugh nt taken frm a specific applicatin f a management infrmatin system, prduced a wide variatin f different types f results and was sufficient fr validating the cmputer mdel. T begin the analysis f this hypthetical manage- ment infrmatin system, a series f three matrices shwing the input and utput relatinships f the dcu- ments that cmprise the system are presented fr cn- venience in Fig. 9. Because f the cmplexity and multitude f the interrelatinships f the data ele- 43

52 M " Ml IS M Fig. 9. Input/Output Relatinships fr a Hypthetical Management Infrmatin System 44

53 merits, these matrices are used In lieu f the general system flwchart as was described in step 1 f Chapter III. Ordinarily a flwchart wuld prve t be very helpful t bserve the verall flw f infrmatin in the system, hwever this example wuld prduce a flwchart that wuld be t cmplicated t be f much value. The numbers that appear as rw and clumn headings n the three matrices crrespnd t the numbers that are assigned by the user fr use in the mdel. Fr a definitin f the data elements that these numbers represent, the Data Element Glssary can be fund in Appendix C alng with all the ther utput reprts that are prduced frm the hypthetical validatin test case. The first reprt that is f interest in Appendix C is the Availibility Matrix (reprt 3). This matrix was checked against the manual slutin, and the tw matrices prved t be identical. Fr further validatin, reprts 4 and 5 were checked in detail against the initial matrices t be sure they yielded crrect results. When further checks were made, it was fund that there were indeed five different pairs f data items and reprts that were input int the same set f input reprts r business functins (with a maximum f nly ne different utput). Thus, these five pairs 45

54 are redundant data element cmbinatins, and reprt 4 appears t be crrect. The final reprt that was checked was the Data Element Fllwup Reprt (reprt 5). Upn scanning the initial matrices, three different data items were fund t be used nly nce in prducing an utput, and nly ne reprt was fund t be used as nly an utput and nt as an input. These were the same results that were printed n reprt 5, thus cncluding the validatin f the cmputer mdel. Since this first test case was a hypthetical case in which the names and types f the data elements were arbitrarily assigned it was nt apprpriate t becme heavily invlved in an analysis f results (tw additinal test cases that are nt hypthetical, but actual applicatins, will subsequently be analyzed). Rather, sme general guidelines n what t lk fr in each reprt are presented, and they will be put int practice later during the analysis f the ther tw test cases. Reprt 3 Availability Matrix The ideal matrix wuld shw nly l's and O's, where this wuld demnstrate that a data item is availible at mst nly ne time t a business functin. Hence, in such a perfect case, ne wuld nt 46

55 be cncerned with duplicatin. Thus, the slutin matrix f reprt 3 shuld be reviewed fr any cell that is greater than ne. Upn finding such a cell, the user shuld g back and find in which reprts the data item is used and shuld then investigate the pssibility f eliminating any f the duplicate surces. Reprt 3 simply gives the user a head start in knwing where t search fr pssible imprvements t the system. Reprt 4 Redundant Data Element Cmbinatins Fr each pair that is listed in this reprt, the user shuld investigate the pssibility f cmbining the tw individual elements that make up the pair int ne dcument. This is especially true when a data item and a reprt have been identified as being redundant. The user shuld ask himself if there wuld be any prblem with including the data item n the reprt in terms f effecting hw the system functins. If n prblems can be identified, the system will be simplified and a certain amunt f redundancy will be eliminated. Reprt 5 Data Element Fllwup Reprt This reprt checks the data elements in the system fr tw different cnditins that have previusly been discussed in Chapter III. The first f these, 47

56 when a data element has been identified as a pssible input parameter, is useful mainly if the infrmatin system being analyzed is autmated (r abut t be). These data elements wuld then prbably be the initial parameters that must bd input int the system individually, as ppsed t being included n a reprt. It lets the user knw which data inputs he will be respnsible fr btaining ther than reprt infrmatin. The secnd cnditin checked fr by the mdel and utput n reprt 5 is that f a pssible nnfunctining element. The identificatin f such a reprt is imprtant because it culd eliminate unnecessary deadweight that the system is prducing. The user shuld check if there is any use whatever fr this reprt in the system. If there is n use fr it, there is n reasn t prduce it. B. Lehigh University Registratin System (TEST CASE 2) The secnd test case that was run n the cmputer mdel was the analysis f the registratin system at Lehigh University. This was the same system that was previusly used.as an example f a dynamic infrmatin system in Chapter II. This system is diagrammed in Fig. 6 f that chapter, and a descriptin f its pera- 46

57 tin is als prvided using the examples f the reprts cntained in Appendix B. Lcated in Appendix D are the five different utput reprts that the cmputer mdel prduced after this test case was run. It shuld be bserved that a few f the data elements are listed as being UPDATED' r 'REVISED' in reprts 1 and 2. This is the case when an infrmatin feedback lp ccurs and a new versin f a dcument is created (a dynamic situatin). In the event a dcument is updated mre than nce dtfring a cycle f the system, the data element name includes the versin number cntained in parentheses. As can be seen frm the utput reprts, the registratin system is designed t prvide tw different business functins : the final student rster, and the final versin f the registratin file. An interesting develpment ccurs when bserving the availability matrix f reprt 3; there are nthing but l»s appearing. The reasn fr this unusual ccurence is the extreme sequential nature f the registratin system where ne reprt is used t prduce the next, which is used t prduce the next, etc., until finally, the business functins are prduced frm nly ne previus reprt which has all the data items availible t it frm all f the previus sequences. Thus, it appears frm 49

58 lking nly at reprt 3 that there is n duplicatin f inputs in the registratin infrmatin system. Hwever, when reprt 4 is subsequently discussed, it will be shwn that there really is redundancy in this system. T further analyze this test case, the user must lk at each pair individually and determine if it is feasible t cmbine the data item with the reprt, r perhaps eliminate the data item frm being input sepairately frm the reprt, if it already is a cmpnent f the reprt. Thus, there are basically three different cnclusins that can be reached regarding each pair f data elements : the elements shuld be cmbined int ne reprt, it is infeasible t cmbine the elements, the data item shuld be eliminated as a separate input. The list f the cmbinatins that were identified by the cmputer mdel and the curses f actin that are perscribed in each instance are included in detail in Appendix D. The results indicate that f the 29 different cmbinatins : data items in 5 f the pairs shuld be eliminated, it is infeasible t cmbine data elements in 18 f the pairs, in 4 f the pairs the data elements shuld be cmbined t A frm a single dcument, and in 2 f the pairs n actin shuld be taken. 50

59 The final utput reprt that was a part f the input/utput analysis fr the Lehigh University registratin system is reprt 5. As was previusly described in this chapter, tw separate cnditins were checked fr in this reprt. The first f these, the pssible input parameter, yielded 19 different data elements. The secnd cnditin, the pssible nnfunctining element, requires further investigatin n the part f the user. After lking at the three candidates fr nnfunctining elements, it appears that the class list may be eliminated frm the system, while the first versin f the updated student rster and the mem t the instructr shuld remain as they are. It wuld appear that the initial class list shuld be eliminated frm the infrmatin system since it is nt used t prduce any ther utput and als because an updated versin is always prduced later in the semester. Thus, the class list is nt serving any purpse in the registratin system. This pint culd prbably be argued by faculty members wh wuld insist that the initial class list is the nly way they will knw which students are in their classes. This is true, hwever the prblem lies in the time delay between when the class list is first issued and when the 51

60 updated versin is made availible. If the prcessing culd be made mre efficient, there wuld be a shrter gap in time between the issuance f the lists and there wuld be n need fr the initial class list in the system. Thus, the current methd f prducing class lists shuld be lked at in mre detail t see if this prblem can be slved. The updated student rster (versin ne) can nt be remved utright frm the system because it nly becmes nn-functining when a student petitins t drp a curse after the deadline has passed. It will be a functining data element if a student nly add/ drps during the semester, in which case it will be used as the final student rster which is ne f the business functins f the system. The reasn fr keeping the mem t the instructr in the registratin prcess is because it actually is serving a functin f the system. That functin is the ntificatin f the curse instructr that ne f his students is n lnger in the curse. In a sense, the data element - mem t instructr culd have been assigned t be a business functin at the beginning f the input/utput analysis, and then it wuld nt have shwn up n reprt 5. Hwever, at the time, it was nt felt t be ne f the imprtant 52