Forum Discussion
Excel Box and Whiskers
Hello ErwinVanLoo,
Box and whisker plots are designed such that data points that are outliers are plotted outside of the "whisker". An outlier is considered to be a data point that is 1.5 times the interquartile above the third quartile or below the first quartile. The interquartile range for this data set is Q3-Q1 or 40-37=3. To determine the range for outliers, that would be:
- Q1-(1.5*3)=37-4.5=32.5
- Q3+(1.5*3)=40+4.5=44.5
So, values below 32.5 and above 44.5 will be plotted outside of the "whiskers". In your data set, since 37 is the lowest data point (and not an outlier), it become the lower "whisker".
I hope this makes sense!
Hello,
Thanks for your reaction, now I understand the reason why Whiskers suddenly appears / disappears.
It's a pitty that the behaviour of the Whiskers is not (well) documented.
Above all it is not the normal behaviour that can be expected from a specific whisker nor from the box and whiskers.
The given reason is not the way we expect that whiskers behave or should behave.
Is it possible to show always the wiskers and not to replace a whisker by a point if the distance is big?
We always need to draw the whiskers in statistical problems, that's why I made one document to have the different graphs (bar graphs, histograms, boxplot...) and in each boxplot I need one box and 2 whiskers.
Is it possible to make changes to the software so that the box and 2 whiskers will always be fully displayed?
Greetings
Erwin
Hello ErwinVanLoo,
If Q1 is equal to the lowest (non-outlier) value of a data set, this will become the lower whisker. Similarly, if Q3 is equal to the highest (non-outlier) value of a data set, this will become the upper whisker. There is no way to change this in excel.
I hope this helps!
Hello PReagan,
Sorry I don't understand your explenation. I took your explanation and have put my values of my first post beside.
I read then:
If Q1 (in my example in the first post is 37) is equal to the lowest (non-outlier) value of a data set (in my example in the firs post = min 32,4999 ??), this will become the lower whisker (No I don't see a Whisker).
This makes no sense. Where didn't I understand your explanation?
Please help me with the values
min = 32
Q1 = 37
Q2 = 39
Q3 = 40
max = 43
to have a graphic with 2 whiskers.
Greetings
Erwin
