This image illustrates my calculation.
The p value I got from the test is 0.000, and the test is a two tailed test with test value=20.
That p value is represented by the far right orange-coloured area.
It is a p value from a two tailed test, but I am doing a one tailed test (Ho: mu < 20), so my...
Oh, sorry I was wrong. His claim applied to the mean. So you were right.
So I did a one tailed test, Ho is "mean difference <20".
The SPSS test I used was one sample t test, I set the test value = 20. The resulting p value = 0.000 (see images below).
I am wondering: how should I do the rest ...
I did a dependent t-test for a medical research, it was comparing before and after measurements.
So the dependent t-test should be the right test to use.
The after measurements have a wide range.
And then the client provided me with another piece of information: "it is very normal...