CH 10 Qusi-Exp

In which of the following circumstances would a researcher be most likely to choose a quasi-experimental research design?

• when there are more than three important confounding variables to control

• when doing research in an applied or natural setting where control is difficult to impose

• when controlling experimenter and participant expectation effects would involve an unacceptable level of deception

• when it is difficult to recruit enough participants to make standard statistical testing valid

When one does not have the ability to , one may consider using quasi-experimental designs.

• measure the dependent variable quantitatively

• randomly assign participants to groups

• manipulate the independent variable

• make multiple measures of the dependent variable

A researcher is carrying out a quasi-experimental study. She has the experimental groups in one lab and a control group in another lab. During the intervention phase of her study, the control school has a small fire that forces participants to leave the lab for one hour. She finds huge differences between the experimental and control groups after the study is completed. While there could be an effect of her intervention, a possible rival hypothesis might be:

• There was a maturation effect

• There was an instrumentation effect

• There was a differential history or selection-history effect

• There was a selection-maturation effect

. The nonequivalent comparison group design can yield several possible outcomes. In one scenario, the experimental group scores higher than the control group at the start of the experiment, and only the experimental group's scores increase from pretesting to posttesting. This could reflect an influence of the independent variable. However, it could also reflect

• a local instrumentation effect.

• a attrition effect both groups.

• simply that the experimental group was studied for a longer time period than the control group.

• selection-maturation effect.

Which of the following threats to internal validity is most likely to be a problem in the nonequivalent comparison group design?

• history

• maturation

• selection bias

• all of the above are potential problems

Visual inspection of the pre- and post-treatment pattern of dependent measure scores is typical of which quasi-experimental design?

• interrupted time series

• non-equivalent control group

• before-after

• factorial

Of the major extraneous variables discussed in this chapter, which is most likely a source of confounding in an interrupted time-series design?

• participant expectations

• history

• attrition

• regression

Which of the following is NOT a quasi-experimental design?

• interrupted time series

• nonequivalent comparison group design

• pretest-posttest control group design

• regression discontinuity design

In a study designed to examine the effects of an intensive reading program, Vaughn et. al (2009) screened 2nd grade students and separated good readers from poor readers. The poor readers were given the intervention treatment. At the end of 26 weeks of intervention significant improvement in the poor readers was noted. What type of experimental design was employed in this study? *

• regression discontinuity

• . nonequivalent comparison group

• interrupted time series

• median split design

If you have conducted a study using the regression-discontinuity design, how would you tell if your treatment had an effect?

• by looking at the data to see if the regression line of the posttest scores differs from the regression line of pretest scores.

• by statistically analyzing the data using Analysis of Variance.

• by comparing the pretest scores with the posttest scores to see if there was a significant change.

• by determining if there is a discontinuity in the regression line for the people above and below the cutoff score.