Regression toward the mean will probably occur in a matched sample when

Regression toward the mean will probably occur in a matched sample when
 
  a. the groups are from different populations.
  b. the groups are randomly assigned from the same population.
  c. the sample is heterogeneous on the dependent variable.
  d. the sample is homogeneous on the dependent variable.
  e. the sample is heterogeneous on the independent variable.

Ques. 2

Identify the threats to internal validity illustrated in the example below. The students who scored extremely high on a test would score lower if given the test again.
 
  a. Instrumentation
  b. Experimental mortality
  c. Selection-maturation interaction
  d. Statistical regression
  e. Diffusion

Ques. 3

To achieve partial control in ex post facto research, the researcher can
 
  a. conduct a pilot study to determine a common cause.
  b. match subjects on as many extraneous variables as possible.
  c. randomly assign subjects to experimental and control groups.
  d. b and c