Contents

GlossaryABAB design (reversal design) A single-subject experimental design in which aninitial baseline stage (A) is followed by a treatment stage (B), a return to baseline (A),and then another treatment stage (B); the researcher observes whether behaviorchanges on introduction of the treatment, reverses when the treatment is withdrawn,and improves again when the treatment is reintroduced.alpha See level of significance.ANOVA The analysis of variance, or ANOVA, is the most commonly used inferentialtest for examining a null hypothesis when comparing more than two means ina single-factor study, or in studies with more than one factor (i.e., independent variable).The ANOVA test is based on analyzing different sources of variation in anexperiment.applied research Research that seeks knowledge that will improve a situation. See alsobasic research.archival records Source of evidence based on records or documents relating the activitiesof individuals, institutions, governments, and other groups; used as an alternativeto or in conjunction with other research methods.attrition See subject attrition.baseline stage First stage of a single-subject experiment in which a record is made ofthe individual’s behavior prior to any intervention.basic research Research that seeks knowledge to increase understanding of behaviorand mental processes and to test theories. See also applied research.block randomization The most common technique for carrying out random assignmentin the random groups design; each block includes a random order of the conditions,and there are as many blocks as there are subjects in each condition of theexperiment.case study An intensive description and analysis of a single individual.causal inference Identification of the cause or causes of a phenomenon, by establishingcovariation of cause and effect, a time-order relationship with cause preceding effect,and the elimination of plausible alternative causes.ceiling (and floor) effect Measurement problem whereby the researcher cannot measurethe effects of an independent variable or a possible interaction effect becauseperformance has reached a maximum (minimum) in any condition of the experiment.central tendency See measures of central tendency.coding The initial step in data reduction, especially with narrative records, in whichunits of behavior or particular events are identified and classified according to specificcriteria.Cohen’s d A frequently used measure of effect size in which the difference in meansfor two conditions is divided by the average variability of participants’ scores(within-group standard deviation). Based on Cohen’s guidelines, d values of .20, .50,and .80 represent small, medium, and large effects, respectively, of an independentvariable.Cohen’s f A measure of effect size when there are more than two means that definesan effect relative to the degree of dispersal among group means. Based on Cohen’sguidelines, an f value of .10, .25, and .40 defines a small, medium, and large effect size,respectively.447