Unlike some experiments in the hard sciences, in psychological ...

[gbarreiro]

Unlike some experiments in the hard sciences, in psychological experiments it is virtually impossible to keep from having some ___________________ _ variables.
 
  Fill in the blank(s) with correct word

Question 2

If a second variable changes along with the levels of the independent variable, that second variable is a(n) ___________________ _ variable.
 
  Fill in the blank(s) with correct word

[jsm54321]

Answer to Question 1

random

Answer to Question 2

confounding