Hi, thank you for the answer!
Yes, this kind of approach seemed strange to me too. But the thing is that we investigated 20 patients and compared their data with a large database of healthy control subjects. That means we did a z-transformation using the reference database (standard procedure in this field (quantitative sensory testing=QST)).
There are other research groups which suggest to then use the 2-sample t-test I mentioned below, because it would be inappropriate to compare data of 20 patients with data of 1200 controls.
So they invented a fictional group with M = 0 and SD = 1 and tested the real data against this fictional data (on a website like http://in-silico.net/tools/statistics/ttest/
--> but Two-Sample T-Test).
To be honest, I have no idea if this is the right approach. My first idea was to do a one-sample t-test and test the patient group (i.e. their z-values) against the value 0 to see, whether the z-values differ significantly from 0.
What do you say?