SOLVED

9.3 Experimental Designs 1)In an experiment, it is essential that the groups be equivalent on ________ at the start of the study. A)the independent variable B)the dependent measures C)participant numbers D)both the independent and dependent variables 2)Two critical factors used to distinguish experimental designs from most nonexperimental designs are A)randomization and equal numbers of participants. B)elimination of all confounds and randomization. C)control groups and randomization. D)sophisticated data analysis and control groups. 3)History, maturation, and regression to the mean can be controlled by including proper A)control groups. B)experimental groups. C)factorials. D)instrumentation. 4)The two characteristics that distinguish experimental designs from nonexperimental designs are A)randomization and sample size. B)sample size and control groups. C)control groups and level of measurement. D)control groups and randomization. 5)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 6)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)random assignment of the researchers. 7)Threats to internal validity from regression to the mean in randomized, posttest-only, control-group designs are controlled by A)nonrandom assignment of participants. B)random assignment of participants to groups. C)controlling for experimental effect. D)random assignment of the researchers. 8)By pretesting the two groups on the dependent variable in a randomized, pretest-posttest, control-group design, we A)rule out variance on all variables of all groups. B)test for initial equivalence on the dependent variable. C)eliminate confounding. D)enhance interrater reliability. 9)In the multilevel, completely-randomized, between-subjects design, participants are randomly assigned to A)one condition. B)two conditions. C)three or more conditions. D)control groups. 10)The randomized pretest-posttest, control-group design is an improvement over the randomized posttest-only, control-group design because A)the former adds an additional control group. B)the latter employs randomization only at the time of the posttest. C)the former adds a pretreatment measurement of the independent variable. D)