Students as a group tend to perform better on the second exam. ...

[lak]

Students as a group tend to perform better on the second exam. This is similar to ______, which is a threat to validity
 
  a. experimenter bias
  b. effects of testing
  c. history
  d. mortality

Question 2

Suppose a researcher is performing an experiment on children. She tests the children on one level of the independent variable at the beginning of the school year, but cannot return to test the second level until mid-April, when the school year is almost completed. What threat to internal validity may be a problem?
 
  a. History
  b. Selection bias
  c. Maturation
  d. Experimenter bias

[matt]

Answer to Question 1

b

Answer to Question 2

c

[lak]

Thanks for the timely response, appreciate it

[mohan]

Gracias!