Suppose an Experiment Wants to Test the Effect Of $x$ On $y$

Suppose an experiment wants to test the effect of $x$ on $y$ on the general public. There are two sessions. In the first session $x=2$ and in the second session $x=4$ . The subject pool in the first session consisted of 50 males and the subject pool in the second session consisted of 50 females. The design is internally valid.