Comments on: Who Ate My Slice? [Chart Review] http://supportanalytics.com/blog/2009/04/who-ate-my-slice-chart-review/ Sat, 30 Apr 2011 08:44:13 -0400 hourly 1 http://wordpress.org/?v=3.1.3 By: Tony http://supportanalytics.com/blog/2009/04/who-ate-my-slice-chart-review/comment-page-1/#comment-3240 Tony Mon, 13 Apr 2009 16:47:26 +0000 http://supportanalytics.com/blog/2009/04/who-ate-my-slice-chart-review/#comment-3240 Jon - I thought I remembered those posts when I saw your comment. I agree that we can avoid this issue by using the format 0.0%. Your second example of the missing slice is unbelievable. Definitely a reason to go with the bar chart. Liu - I didn't create the chart and listed the source as from BusinessWeek. You may be able to find out by contacting them directly. I think the default font - arial, enlarged and bold looks pretty good. Jon – I thought I remembered those posts when I saw your comment. I agree that we can avoid this issue by using the format 0.0%. Your second example of the missing slice is unbelievable. Definitely a reason to go with the bar chart.

Liu – I didn’t create the chart and listed the source as from BusinessWeek. You may be able to find out by contacting them directly. I think the default font – arial, enlarged and bold looks pretty good.

]]> By: Liu's chart blog http://supportanalytics.com/blog/2009/04/who-ate-my-slice-chart-review/comment-page-1/#comment-3239 Liu's chart blog Mon, 13 Apr 2009 12:50:30 +0000 http://supportanalytics.com/blog/2009/04/who-ate-my-slice-chart-review/#comment-3239 Tony - What 's the font of the numbers in the chart ? I wanna install it . Tony -
What ‘s the font of the numbers in the chart ? I wanna install it .

]]> By: Jon Peltier http://supportanalytics.com/blog/2009/04/who-ate-my-slice-chart-review/comment-page-1/#comment-3238 Jon Peltier Mon, 13 Apr 2009 12:27:28 +0000 http://supportanalytics.com/blog/2009/04/who-ate-my-slice-chart-review/#comment-3238 Tony - Usually for people like you (uh, us) there is a disclaimer, "Numbers may not add to 100 due to rounding". There is a real problem with <a href="http://peltiertech.com/WordPress/pie-chart-rounding-in-excel/" title="Pie Chart Rounding in Excel" rel="nofollow">Pie Chart Rounding in Excel</a>. If you show percentage labels with no decimal percentages, the percentages are forced to sum to 100, and if the rounded whole-number percentages don't add up, Excel arbitrarily adjusts the displayed percentages. This can be almost meaningless, showing 33-33-34 for equal thirds, but for more intricate data sets, similar values can be adjusted in a strange and wondrous manner, for example, percentages of 21-21-21-13-8-8-8 (which add to 100, by the way) being displayed as 22-20-21-13-8-8-8 in 2003 and as 23-21-21-13-8-7-7 in 2007. To solve the problem use a number format of 0.0% instead of 0%. Apparently the designers of Excel decided that people who can understand decimal percentages don't require that the pie wedges add to exactly 100. Of course, there are cases where the inputs to a pie chart do not add to 100%, as described in <a href="http://peltiertech.com/WordPress/pie-chart-plotting-deficiency/" title="Pie Chart Plotting Deficiency" rel="nofollow">Pie Chart Plotting Deficiency</a>. Instead of including a wedge for "Other 10%", they left it off. But the chart looks pretty. Tony -

Usually for people like you (uh, us) there is a disclaimer, “Numbers may not add to 100 due to rounding”.

There is a real problem with Pie Chart Rounding in Excel. If you show percentage labels with no decimal percentages, the percentages are forced to sum to 100, and if the rounded whole-number percentages don’t add up, Excel arbitrarily adjusts the displayed percentages. This can be almost meaningless, showing 33-33-34 for equal thirds, but for more intricate data sets, similar values can be adjusted in a strange and wondrous manner, for example, percentages of 21-21-21-13-8-8-8 (which add to 100, by the way) being displayed as 22-20-21-13-8-8-8 in 2003 and as 23-21-21-13-8-7-7 in 2007.

To solve the problem use a number format of 0.0% instead of 0%. Apparently the designers of Excel decided that people who can understand decimal percentages don’t require that the pie wedges add to exactly 100.

Of course, there are cases where the inputs to a pie chart do not add to 100%, as described in Pie Chart Plotting Deficiency. Instead of including a wedge for “Other 10%”, they left it off. But the chart looks pretty.

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