Experimental Research Designs – Practice Flashcards

Fifteen question-and-answer flashcards covering key points about experimental research designs, validity threats, variance, control groups, and solutions to common methodological issues.

What four elements are specified in a research design?

Number of IVs and DVs, number of measurements of the dependent variables, number of experimental/control groups, and the way participants are assigned and sampled.

Which central feature of an experiment allows researchers to establish causal direction?

Direct manipulation of the independent variable before measuring the dependent variable.

How is ‘exclusivity’ (internal validity) achieved in an experiment?

By isolating the independent variable and using an equivalent control group that differs only on that variable.

Why do experiments provide greater sensitivity and statistical power than field studies?

Because the researcher controls the intensity of the independent variable and can fine-tune its levels.

What advantage of experiments is highlighted by the ability to repeat a study with new participants under identical conditions?

Reliable replication (repeatability).

Which two main threats to internal validity endanger a one-group pretest–posttest (before–after) design without a control group?

History and maturation (plus measurement, instrumentation, regression to the mean).

What three characteristics turn a design into a ‘true experiment’?

Random assignment, a control (or comparison) group, and experimental control over variables/procedures.

What problem does the Solomon four-group design test for, and how?

Interaction between pretesting and the treatment; it compares groups with and without pretests to detect pretest effects.

Why might a posttest-only control group design be chosen over a pretest–posttest design?

It avoids pretest reactivity and interaction between the pretest and the treatment while still benefiting from randomization.

In analysis of variance, what do the terms ‘between-group variance’ and ‘within-group variance’ represent?

Between-group variance is systematic variance due to the manipulation; within-group variance is random error originating from individual differences and measurement noise.

How does random assignment reduce systematic error (bias) between groups?

It distributes extraneous variables equally across groups, making them unlikely sources of between-group differences.

Name three methods for constructing an appropriate control group.

Randomization, matching participant characteristics, and holding a potential confounding variable constant.

What are ‘order effects’ in repeated-measures designs, and give two examples.

Changes in performance caused by the sequence of conditions; examples include fatigue and practice (learning) effects.

For what purpose is a Latin Square (counterbalancing) arrangement used?

To ensure every treatment condition appears in every ordinal position and follows every other condition equally often, controlling order effects.

Placebo, empty control, and compensatory comparison groups are all examples of what experimental element?

Different types of control groups used to isolate the effect of the independent variable.