When should a paired t test be conducted?

I. There are 2 independent samples. The samples are drawn from different or independent populations. The means of each sample are used to derive the test statistic.

II. There are dependent samples. The samples are drawn from the same population or dependent populations. The means of the difference of the dependent observations are used to derive the test statistic.

III. There is only one sample. This sample is divided into 2 sub-groups. The means of each sub group are used to derive the test statistic.

Group of answer choices

I only

II only

III only

None of the listed choices