1. ## Sign Test

https://imgur.com/a/CfwpZ

https://imgur.com/a/nCM0I

https://imgur.com/a/P2SQK

In the photo above ,
H0 = the position of the plant doesnt affect the number of seeds in the pods .
H1 = position of the plant affect the number of seeds in the pods

This is a two -tailed test , am i right ? Referring to the normal distribution table , z α=0.05 = 1.645 , z α/2=0.025 = 1.960 ... In the example , it's clear that the author use one -tailed test . I think it's wrong . He should use z α/2=0.025 = 1.960 , Am i right ? Correct me if i am wrong .

2. ## Re: Sign Test

Yes, there is a mismatch between the problem formulation (two-tailed) and the way the Z-statistic is evaluated (one-tailed).

3. ## Re: Sign Test

Originally Posted by stans
Yes, there is a mismatch between the problem formulation (two-tailed) and the way the Z-statistic is evaluated (one-tailed).
So, should it be two tailed test and 0.5alpha =0.0025 is used?

4. ## Re: Sign Test

Originally Posted by stans
Yes, there is a mismatch between the problem formulation (two-tailed) and the way the Z-statistic is evaluated (one-tailed).
Or i could be wrong ? For sign test , alpha is taken as one tailed value although it's 2 tailed test ??