Author Question: In the randomized, posttest-only, control-group design, external validity is protected by A) ... (Read 60 times)

leo leo · **on:** Aug 4, 2018

In the randomized, posttest-only, control-group design, external validity is protected by

A) random selection of the sample.
B) random assignment of participants to groups.
C) use of a control group.
D) None of the above

Question 2

In order to test the effects of the 1988 heat wave on worker productivity, 48 machinists were randomly assigned to two groups of 24 machinists each.

Each group was tested at a different room temperature (cool and hot) using dependent measures of number of parts produced and accuracy. What type of design does this study represent?

A) a single-group, pretest-posttest design
B) a Solomon four-group design
C) a multilevel, completely randomized, between-subjects design
D) a randomized, posttest-only, control-group design