I have set up a spreadsheet to demonstrate to students how to calculate standard deviation. The result that I have calculated matches the result given with the data, from the source. However, it differs from the result of the spreadsheet formula…

=STDEV(B2:B20)

Is anyone able to explain why the function STDEV might not give the result expected?

I shall be happy to share my spreadsheet if attachments are possible on this forum?

The data set I am working with is available here:

https://www.rgs.org/CMSPages/GetFile.aspx?nodeguid=2bc6c27a-7d33-402f-b327-e6bec35af7be

My step by step spreadsheet calculations involve…

(1) Calculate the mean.

(2) Subtract the mean from each value in the set.

(3) Calculate the square of each value in (2).

(4) Sum the vales from (3).

(5) Divide (4) buy n.

(6) Take the square root of (5).