Record high temperature How many states Class Midpoint Label 94.5 99.5 94.5-99.5 0 97 99.5 104.5 99.5-104.5 2 102 102 104.5 109.5 104.5-109.5 8 107 107 109.5 114.5 109.5-114.5 18 112 112 114.5 119.5 114.5-119.5 13 117 117 119.5 124.5 119.5-124.5 7 122 122 124.5 129.5 124.5-129.5 1 127 127 129.5 134.5 129.5-134.5 1 132 132 134.5 139.5 134.5-139.5 0 137 Note that for a Frequency Polygon, we label the horizontal axis with the class midpoints and we put markers above those midpoints, (whereas the Histogram was oriented toward Class Boundaries.) The book adds a column for Class Midpoints. Class Midpoint formula in cell F2: =AVERAGE(A2,B2) and that formula is copied to the rest of the Class Midpoint cells. The purple is additional stuff we are adding to make Excel produce the chart. There's an extra class at either end with frequency 0. Those extra classes will have a blank label on the horizontal axis. Gray area is not in the Yellow: This is the table of book. Instead of data printed in the text, typing in all the ranges, but our headings are more descriptive. we put 99.5 in A2 In Cell D2, the formula is: =A2&"-"&B2 then in B2, formula =A2+5 Copy the D2 formula and Paste it into D3:D8 In A3, formula =B2 Copy the A3 formula and Paste it into A4:A8. Copy the B2 formula and Paste it into B3:B8 "Wrap Text" and adjust column widths to get the column headings to fit.
CREATE THE FREQUENCY POLYGON Select the numbers in the "How many states" column of the Frequency Distribution. (That is, click on the first cell, hold down the left mouse button, and drag until you've got them all selected. Click the "Insert" tab on the ribbon and in the "Charts" section, Click on "Line" and select the "Line with Markers"
How many states Here is the Frequency Polygon. Notice that it is anchored to the horizontal axis on the left and on the right, thanks to the two extra bins we put at the ends of our frequency distribtuion. 20 18 16 14 12 10 8 6 4 2 0 1 2 3 4 5 6 7 8 9 Series1 Improvements - Titles We add (1) a chart title and (2) a horizontal axis title and (3) a vertical axis title and (4) we remove the legend, the "Series1" thing on the right side. 20 15 All-time Record High Temperatures Details of how to do this are the same as already presented in the Histogram example, and the instructions are not repeated here. 10 5 0 1 2 3 4 5 6 7 8 9 Temperature ( F)
One remark about the titles: This time we added the "( F)", degrees Fahrenheit, to the horizontal axis title.. How did we get the degree symbol? The "Insert" command on the Ribbon, and at the far right there's a section for Symbols with "Symbol" on it. You don't have to pick the "Subset: Latin-1 Supplement"; you can scroll through all the Subsets using the scroll bar at the right. When you find the degree symbol, highlight it and click "Insert". Then you'll see a "Close" button; click it to dismiss the Symbol dialog. (or insert more special symbols and then click the Close when you're done.)
Horizontal Axis Labels: As with the Histogram, Excel has given us 1, 2, 3, 4, but we want the Class Midpoints. We right click on the axis (it's a little tricky to get Excel to highlight just the axis, just try it and keep trying until you get it..) You'll see a dim gray border around the axis labels when you've got it. (An alternative is in the Ribbon, Chart Tools, Design, and there's a Select Data icon there.) In the "Select Data Source" box, on the right side, is where the Horizontal Axis Labels are determined. You can see the bad 1, 2, 3, values that Excel put in. Click the Edit button to begin changing them.
The "Axis Labels" dialog wants an "Axis label range". Don't type directly into that box. Instead, go to your table and highlight the data labels. Select all those cells (see how Excel highlights the cells you're selecting) including the blank one at the beginning and the end. Click OK in the "Axis Labels" dialog. Back in the "Select Data Source" box, we can see our new values are there. Click "OK".
How many states Here is the improved chart with the correct labels on the Horizontal Axis. 20 All-time Record High Temperatures There is one more slight change. We want the tickmarks to be immediately above the class midpoints (see how the 102, for instance, is between two tickmarks). 15 10 5 0 102 107 112 117 122 127 132 Temperature ( F) Right click on the axis (tricky to do, remember look for the gray outline. And choose "Format Axis " from the pop-up menu. Alternative to the right clicking: Use the ribbon, Chart Tools, Layout, Axes, Primary Horizontal Axis, More Horizontal Axis Options)
How many states In the "Axis Options", look for "Position Axis" and change it to be "On tick marks" Here is the result: All-time Record High Temperatures 20 15 10 5 0 102 107 112 117 122 127 132 Temperature ( F)
How many states Our vertical axis is just fine, labeled from 0 to 20, stepping by 2. If we wanted to match the book's picture of 0 to 18 stepping by 3, select the axis (right click) and in the Axis Options, make one little change in this case. (You have many more options to control the numbering but here, we just needed one change). (Two changes if we wanted to force it to stop at 18 and not include the 21.) All-time Record High Temperatures 21 18 15 12 9 6 3 0 102 107 112 117 122 127 132 Temperature ( F)
Incomplete: How to leave some blank space between the intersection of the axes and where the point (97,0) is plotted. Same observation about the Histogram.