A researcher conducts a two-sample t test comparing the mean sociability levels of 20 psychology majors and 15 chemistry majors. How many degrees of freedom are there for this test?

Question

A researcher conducts a two-sample t test comparing the mean sociability levels of 20 psychology majors and 15 chemistry majors.  How many degrees of freedom are there for this test?

qiqi · Answer

I do not remember my statistics very well. However,

from what I remember, sample tests usually can be represented as $(N-1)$. N is the sample size and 1 is the parameter/relationship. So in your case you will have:

$$ DoF = (n_1-1) + (n_2-1)$$

where your $n_1$ can be your "20 psychology majors" samples, and $n_2$ can be your "5 chemistry majors" samples. All you  have to do is plug in these variables into the formula.