If physical control, randomization, and design features do not ...

[V@ndy87]

If physical control, randomization, and design features do not eliminate the differential effects of extraneous variables among treatment groups, the experiment
 a. has been confounded, but causal statements are still possible
  b. has been confounded, and no causal statements are possible
  c. must be repeated without the presence of extraneous variables
  d. loses external validity, but can still salvage internal validity

Question 2

As sample size increases, the distribution of sample means of samples of size n (when randomly selected) approaches a normal distribution is a fundamental assumption of the central-limit theorem.
 
 Indicate whether the statement is true or false

[ErinKing]

Answer to Question 1

B
If the effects of extraneous variables cannot be eliminated, then the experiment has been confounded and the researcher cannot imply any causation.

Answer to Question 2

T