Contents

Subject Index 487defined, 123, 204, 356–357estimated standard error of themean and, 357Standard error of the meancalculation of, 357defined, 357sample size and, 357Statistical regression. See Regression(to the mean)Statistical significance. See also Nullhypothesis significance testing(NHST)alpha and, 208, 385critical values, 208–209, 392defined, 208, 385interpretation of, 210–211, 385–388,393, 401, 406level of significance, 208, 385power and, 388–390scientific or practical significanceand, 392–393tables to determine, 444–446tests of, 208–210. See specific testsStatistical tests. See Inferentialstatistics; Null hypothesissignificance testing (NHST); alsospecific statistical testsStatistically significant (defined), 208,210–211, 393Stem-and-leaf display, 352–354Stratified random sampling, 147–148Structured observation, 103–105, 130Subject attrition (loss)longitudinal design and, 160–161mechanical, 197selective, 197–200threat to internal validity,197–200, 317Subject loss. See Subject attrition(loss)Subject selection threat to internalvalidity. See Selection threat tointernal validitySubject variable. See Individualdifferences variableSubtraction method, 259–260Successive independent samples design(survey research), 155–157Sum of squares. See Analysis ofvariance (ANOVA; F-test)Summarizing the data, 202, 347–348,355–360, 372–377Survey researchbias in, 143–145, 149–153, 160–161,174–175characteristics of, 138–140correlational research and, 138,175–177cross-sectional design, 154–155designs, 154–161ethical issues, 139–140, 153Internet surveys, 152–154longitudinal design, 158–161mail surveys, 148–149margin of error and, 361methods, 148–154personal interviews, 150questionnaire asinstrument, 161–164questionnaire construction and,167–173random digit dialing, 151reactivity and, 173–175reliability of, 164–167sampling techniques, 140–148social desirability and, 174successive independent samplesdesign, 155–157telephone interviews, 151–152uses of, 138–140validity of, 164–167Systematic variation, sources of, 262.See also Analysis of variance(ANOVA)Telephone survey, 151–152Testimonials, evaluating, 290–291Testing intact groups, 195Testing (threat to internal validity), 315Test-test reliability, 164–165Tests of statistical significance. SeeNull hypothesis significancetesting (NHST); also specificstatistical testsTheorycase study and, 285–287characteristics of, 50confirmation of, 52defined, 50–51development of, 50, 272–275experiments and, 185–186, 272–275falsifying, 53functions of, 50–51hypotheses and, 39interaction effects and, 268–269,272–275intervening variables and, 51–52scientific, 49–53scope, 50testing, 52–53, (See also Analysis ofData) 268–269Threats to internal validity. See alsoControl techniquesadditive effects withselection, 317–318contamination, 319, 330defined, 195, 315history, 315instrumentation, 316local history, 329maturation, 315novelty effects, 319–320, 330–331practice effects and, 229–230regression, 316–317selection, 317subject attrition (loss), 197–200, 317testing, 315–316testing intact groups, 195true experiments and, 314–318Time-order relationship (and causalinferences), 46–48, 187, 193Time sampling, 94–95Time series with nonequivalentcontrol group design,335–336Transformation of data, 351Treatment. See Experimentalcondition; Independentvariable; Manipulation;Natural treatmentTreatment stage vs. baseline stage,293–295True experiment, 187, 311–321. Seealso Experimentt-testcomparison of two meansand, 208, 371, 390, 405independent groups, for,208, 391repeated measures, for, 243,391–392table of critical values, 444Two-mean comparison. SeeComparison of two meansType I error, 210–211, 387–388Type II error, 210–211, 387–388Understanding as goal of scientificmethod. See Explanation as goalof scientific methodUnobtrusive (nonreactive) measuresarchival data, 110–112defined, 107ethical issues, 130indirect observation and, 106–107physical traces, 107–109products, 107,109reactivity and, 107, 127–129types, 107use traces, 107–108validity of, 109Use traces (unobtrusive measures)controlled vs. natural, 108types, 107Utilitarianism, 81Validity (types)construct, 35, 164–167convergent, 164–167, 185defined, 38discriminant, 164–167external, 94, 211, 214, 321internal, 187, 195, 315–318Variability (measures). See Errorvariation; Measures ofdispersion