Compound bar chart - to round or not to round? (percentages)

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SUMMARY

The discussion centers on the best practices for displaying percentages in a compound bar chart, particularly when dealing with non-integer values. Participants agree that rounding can be done to a significant number of decimal places, but it is essential to round normally, where 0.5 rounds up and values below 0.5 round down. It is also acknowledged that rounding errors may lead to totals not equaling 100%, which is a common occurrence and should not be a concern.

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  • Understanding of compound bar charts and their structure
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Data analysts, data visualization specialists, and anyone involved in creating compound bar charts who seeks to enhance their understanding of percentage representation and rounding practices.

3vo
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Hi guys,

I'm currently drawing a compound bar chart.
As I understand, this is type of bar chart which involves sub data within each grouping. The sub data is incorporated into each of their grouping bar as a percentage out of 100% of that bar. So basically the bar is 100% in total and the sub data is drawn into the bar, as their respective percentage of the bar. (I could of prob explained that a lot better).

Anyway... I've drawn up my chart and worked the percentages of each sub data within each grouping out of a 100%. However for some of the groups, the sub data are NOT integers.

Do I round these figures up to a whole number? or a specific number of dp or sf? What do I do if after rounding the total doesn't add up to 100%?

Or is it better to leave them as they are and try to best incorporate them into the graph?

An example of my data: Imagine a table below (dont know how to do one here)
First number is freq, 2nd is %
Monday | Tuesday |
Red 7 30.'43% 3 18.75%
Blue 10 43.'47% 7 43.75%
Black 6 26.08% 6 36.5%
Totals 23 100% 16 100%
 
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3vo said:
Do I round these figures up to a whole number? or a specific number of dp or sf? What do I do if after rounding the total doesn't add up to 100%?

Or is it better to leave them as they are and try to best incorporate them into the graph?

Hi 3vo! :)

Yep. Leave them as they are, or round them to some significant number of digits.
Up to you basically. What you think looks best and is most informative.

But if you do round them, don't round up, but round normally.
0.5 goes up, 0.4999 goes down.

And if they don't add up to 100%, don't worry about it.
That's normal - the result of rounding errors.
This is known and accepted.
 

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