A company was interested in learning if training expenditures ...

[Garrulous]

A company was interested in learning if training expenditures will enhance its salesforce productivity, so they hired a researcher to conduct an experiment in which one group of salespeople received training and the other didn't. The average sales for salespeople who received training was significantly higher than for those who did not. This difference in means between the two groups is known as a(n) _____ effect.
 a. placebo
  b. main
  c. covariate
  d. interactive

Question 2

_______________ is a data-based selection bias that occurs when data are deemed bad using arbitrary criteria, often as they come in, instead of using explicitly-stated or previously agree-upon standards.
 a. Endpoint selection c. Premature termination
  b. Ad hoc rejection d. Drop-out bias

[lindahyatt42]

Answer to Question 1

B

Answer to Question 2

B
With ad hoc rejection, the researcher decides arbitrarily that a piece of data looks bad and is, therefore, rejected.