Mortality is a threat to the validity of a study that is caused ...

[Mimi]

Mortality is a threat to the validity of a study that is caused by _____.
 
  a. the lack of random assignment
  b. having only one group of subjects
  c. comparing subjects who are at different stages of development
  d. some subjects failing to complete the study

Question 2

In inferential statistics random sampling is regarded as desirable but not essential.
 
  Indicate whether the statement is true or false

[yotaSR5]

Answer to Question 1

D
Mortality refers to the drop-out rate.

Answer to Question 2

F