2.2 Grouping Data. Tom Lewis. Fall Term Tom Lewis () 2.2 Grouping Data Fall Term / 6

Transcription

1 2.2 Grouping Data Tom Lewis Fall Term 2009 Tom Lewis () 2.2 Grouping Data Fall Term / 6

2 Outline 1 Quantitative methods 2 Qualitative methods Tom Lewis () 2.2 Grouping Data Fall Term / 6

3 Test scores Here are the scores for the first test in an Introductory Statistics class: How can we present this data? Tom Lewis () 2.2 Grouping Data Fall Term / 6

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6 Frequency: The number of observations that fall in a class

7 Frequency: The number of observations that fall in a class Relative frequency: The ratio of the frequency of a class to the total number of observations

8 Frequency: The number of observations that fall in a class Relative frequency: The ratio of the frequency of a class to the total number of observations Relative frequency distribution: A listing of all classes and their relative frequencies

9 Frequency: The number of observations that fall in a class Relative frequency: The ratio of the frequency of a class to the total number of observations Relative frequency distribution: A listing of all classes and their relative frequencies Lower cutpoint: The smallest value that could go in a class.

10 Frequency: The number of observations that fall in a class Relative frequency: The ratio of the frequency of a class to the total number of observations Relative frequency distribution: A listing of all classes and their relative frequencies Lower cutpoint: The smallest value that could go in a class. Upper cutpoint: The smallest value of the next higher class.

11 Frequency: The number of observations that fall in a class Relative frequency: The ratio of the frequency of a class to the total number of observations Relative frequency distribution: A listing of all classes and their relative frequencies Lower cutpoint: The smallest value that could go in a class. Upper cutpoint: The smallest value of the next higher class. Midpoint: The middle of a class; the average of the cutpoints.

12 Frequency: The number of observations that fall in a class Relative frequency: The ratio of the frequency of a class to the total number of observations Relative frequency distribution: A listing of all classes and their relative frequencies Lower cutpoint: The smallest value that could go in a class. Upper cutpoint: The smallest value of the next higher class. Midpoint: The middle of a class; the average of the cutpoints. Width: The difference between the cutpoints of a class.

13 Problem A fair die was rolled 20 times; here are the outcomes of the tosses How should we group and display the data? Tom Lewis () 2.2 Grouping Data Fall Term / 6

14 Qualitative methods Problem A pack of 55 m&m s was opened and the candies were withdrawn one at a time. Here is the list of their colors. g y br g o br r br g o br r g g g bl bl r g bl o g o br br g br y o br g o bl o bl r o bl o o g br bl o o r g br g br br g r y y How can we group and display this data? Tom Lewis () 2.2 Grouping Data Fall Term / 6