Hi,

i can be wrong but i know sign test like that. I havent understood your formula but you can understand test's sense from below.

Also , you can look this link for more information:

http://caspar.bgsu.edu/~courses/Stats/Lectures/Lect_SignTest.html
Also ,ask it to uncle google. Just write "sign test".

firstly,

17-20= -3 (-)

15-20=-5 (-)

...

...

...

24-20=4 (+)

we sum (-) ones.

we sum (+) ones.

we dont sum datas , we only sum (-) and (+) signs.

In your data , i can see 3 negatives and 7 positives. We choose minumum one so we will work with negatives.

And than , we look sign test table,

We should look k= 3 and n=12.

Our table value = 0.073

alfa=0.05 , table value > alfa ; so we accept Ho hypothesis.

Signt test table,