calculate S.D. of differences using excel

[jb]

hi experts,

i have two columns A and C with 100 entries in each. Column A represents score of odd statements of a questionnaire and Column C represents score of odd statements of a questionnaire. Column E is difference between column A and C. Column G is sum between column A and C.

I have calculated Mean, SD and SD square for column A and C. I want to calculate
1. standard deviation of differences and
2. SD of whole data
using excel.

Help required. Attaching sample file with this.

 

[Hui]

Wouldn't
A1. =STDEV(E1:E100)

A2. =STDEV(A1:A100,C1:C100)
A2 is correct as if you use: =STDEV(A1:A50,A51:A100)
it compares precisely to J5

 

[jb]

Thanks Hui. Thanks a lot.........
You don't know that what you have done for me.
Thanks once again.