Compound bar chart - to round or not round percentages?

  • Thread starter 3vo
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In summary, the speaker's task is to draw a compound bar chart, where each group of data is represented by a single bar and the sub data within the group is divided into a percentage of the total 100%. They are unsure how to incorporate fractions/decimals into the graph and question whether to round up or down. They suggest rounding the numbers to 2 significant figures and adding or subtracting the extra from the largest percentage to ensure a total of 100%. However, they also mention the importance of drawing the chart as accurately as possible, even if 0.5% may not be visible.
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3vo
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Homework Statement


Hi,
My task is to draw a compound bar chart. As I understand, with this type of bar chart; each group of data is represented by a single bar which is equivalent to 100%. The sub data within that group is divided into a percentage of the total 100% and drawn into the grouping bar, splitting the bar into percentage counterparts of the whole bar.

The problem is for some of my data which initially are integers but when calculating percentages become fractions/decimals (some repeating). I don't know how to use this data when incorperating into my graph. Do I round up or down? or try to best draw them into my graph.

Normally I would round my answer to the same number of dp or sf as the lowest value in the question. However in this case, my initial numbers are integers, so if I round up or down to the same number of SF or DP, the total sum of my percentages do not add up to 100%.

In this case, (similiar to if I were doing a pie chart) do I round to the nearest whole number and than add or subtract whatever remains from the largest percentage value as it would make the least diff?

Homework Equations


Imagine a table below:

Mon Tues Wed
Red 7 (30.'43%) 3 (18.75%) 2 (20%)
Blue 10 (43.'47%) 7 (43.75%) 6 (37.5%)
Black 6 (26.'08%) 6 (37.5%) 5 (50%)
Total 23 (100%) 16 10

The Attempt at a Solution



Round the numbers to 2 sf and add or subtract the extra from the largest percentage.
So for monday
Red: 30
Blue: 43
Black: 26
total: 99

Add remaining 1% to blue (43+1=44) to now have a total of 100% as it makes the least difference adding to largest percentage.

Would this be the correct method?

Thanks in advance
 
Last edited:
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  • #2
Draw them as accurate as possible (a computer will do that anyway, by hand see how accurate you can draw it, I guess .5% are not visible), and display the percentages rounded to integers. The sum is 100%, even if 30+43+26=99, that is okay.
 

1. Should I round the percentages in a compound bar chart?

The decision to round or not round percentages in a compound bar chart depends on the purpose of the chart and the level of precision needed. If the chart is being used for general visualization and the exact values are not critical, rounding can help simplify the chart and make it easier to read. However, if the percentages are being used for precise comparison or analysis, it may be necessary to keep the values unrounded.

2. Will rounding the percentages affect the accuracy of the chart?

Yes, rounding the percentages will affect the accuracy of the chart. Rounding introduces a small amount of error, which may not be significant for general visualization but can impact the precision of the data. Therefore, it is important to consider the level of accuracy needed for the specific use of the chart before deciding whether or not to round percentages.

3. Can I round the percentages to a certain decimal place?

Yes, you can round the percentages to a specific decimal place. This is usually done for consistency and to improve the readability of the chart. However, it is important to note that rounding to a specific decimal place may introduce more error compared to rounding to the nearest whole number. This should be taken into consideration when deciding on the level of rounding for the percentages.

4. What is the impact of not rounding percentages in a compound bar chart?

The impact of not rounding percentages in a compound bar chart is that the chart may appear more complex and harder to read. This can be a disadvantage if the chart is being used for general visualization. However, not rounding percentages allows for more accurate data representation and can be beneficial for precise comparison or analysis.

5. How do I decide whether to round percentages in a compound bar chart or not?

The decision to round percentages in a compound bar chart ultimately depends on the purpose of the chart and the level of precision needed. Consider the specific use of the chart and whether or not the exact values are critical for the analysis or comparison being made. It may also be helpful to consult with others or conduct a small test to determine the best approach for your specific situation.

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