Question

Whwn confunding is present, we cannot distinguish the effects of______ from the effects of _______ on the response variable

Answer 1

Essentially, a confounding variable will distort the correlation of the outcome being examined against the causal effect.

When confounding is present, we cannot distinguish the effects of direct modification from the effects of random error on the response variable

There can be many ways to fill the words here. But the essence is that, a confounding variable creates a sort of triangular relationship with the root cause of study and the response variable. It may positively or negatively reinforce the causal effect. Apart from that, we can also expect random error of observation. These effects become intermingled and which effect is influencing to what extent is difficult to isolate.