The central threat to the internal validity of a simple ...

[ghost!]

The central threat to the internal validity of a simple interrupted time series design is
 
  a. maturation
   b. contemporary history
  c. regression to the mean
  d. pretest sensitization
  e. selection bias

Question 2

A local history effect occurs
 
  a. because participants were not randomly assigned to groups
  b. when external validity is low
  c. as a result of regression to the mean
  d. all of the participants are from the same locality
   e. when groups experience different events other than the quasi-independent variable

[xMRAZ]

Answer to Question 1

B

Answer to Question 2

E