Consider this text:
Researchers conducted two different types of test on a large group of people. After that, the researchers subjected the people to situations like Z and noted their response R. Those with high scores on test T2 had a good response. Likewise, those with low scores on test T2 had a bad response. Therefore, researchers conclude that the score of test T2 affects the response R.
Fact 1: Score of test T1 affects response R.
Fact 2: Score of test T1 affects score of test T2.
Fact 3: Score of test T2 does not affect the response R.
Here, the researchers wrongly assumed that the score of test T2 affects the response R.
However, it is not true because the real culprit is test T1. What logical fallacy(s) did the researchers made?