Contents

452 Glossaryparticipant observation Observation of behavior by someone who also has an activeand significant role in the situation or context in which behavior is recorded.physical traces Source of evidence that is based on the remnants, fragments, and productsof past behavior; used as an alternative to or in conjunction with other researchmethods.placebo control group Procedure by which a substance that resembles a drug orother active substance but that is actually an inert, or inactive, substance is given toparticipants.plagiarism Presentation of another’s ideas or work without clearly identifying thesource.population Set of all the cases of interest.positive correlation A relationship between two variables in which values for onemeasure increase as the values of the other measure also increase.power Probability in a statistical test that a false null hypothesis will be rejected; poweris related to the level of significance selected, the size of the treatment effect, and thesample size.practice effects Changes that participants undergo with repeated testing. Practice effectsare the summation of both positive (e.g., familiarity with a task) and negative(e.g., boredom) factors associated with repeated measurement.privacy Right of individuals to decide how information about them is to be communicatedto others.probability sampling Sampling procedure in which the probability that each elementof the population will be included in the sample can be specified.program evaluation Research that seeks to determine whether a change proposed byan institution, government agency, or other unit of society is needed and likely tohave an effect as planned, and, when implemented, to have the desired effect at areasonable cost.quasi-experiments Procedures that resemble characteristics of true experiments, forexample, that some type of intervention or treatment is used and a comparison is provided,but are lacking in the degree of control that is found in true experiments.questionnaire A set of predetermined questions for all respondents that serves as theprimary research instrument in survey research.random assignment Most common technique for forming groups as part of an independentgroups design; the goal is to establish equivalent groups by balancing individualdifferences.random groups design Most common type of independent groups design in whichsubjects are randomly assigned to each group such that groups are considered comparableat the start of the experiment.random sampling See simple random sampling.range The difference between the highest and lowest number in a distribution.reactivity Influence that an observer has on the behavior under observation; behaviorinfluenced by an observer may not be representative of behavior that occurs when anobserver is not present.regression (to the mean) Statistical regression can occur when individuals have beenselected to participate in an experiment because of their ”extreme” scores. Statisticalregression is a threat to internal validity because individuals selected from extremegroups would be expected to have less extreme scores on a second test (the “posttest”)without any treatment simply due to statistical regression.relevant independent variable Independent variable that has been shown to influencebehavior, either directly, by producing a main effect, or indirectly, by resulting in aninteraction effect in combination with a second independent variable.