# Two-sample test + paired/independent samples

This might be an easy question but I got lost in my thinking so thank you for clarifying that for me. So I have some troubles with understanding the ideas of two-sample tests in addition to paired and independent sample tests.

So this is clear for me:

• Two-sample test is used to determine a difference between two independent populations. So an example would be comparing the mean alertness after drinking coffee among men and women.

• Paired and independent samples tests determine the method of collecting results. For example: let's say we want to determine what increases alertness more - energy drinks or coffee. In paired samples test we make each subject drink coffee and then perform a test and the next day we give them energy drink and perform the test again. In independent samples test we divide people into two groups and make the one drink coffee and the other energy drink.

Is it possible to connect these two concepts? From my understanding two-sample tests are independent samples tests because by definition the populations need to be independent. Though I'm not sure if this reasoning is correct. Is there anything like two-sample paired test?