24.1

I-1

Note: Page numbers followed by f indicate figures; those followed by t indicate tables.

Abbreviations, APA guidelines for, 8182

Abumrad, J., 105

Adams, J., 139, 152, 177, 237

Airy, George, 126

Ali, N., 336

Alphas (p levels), 168, 201, 201f

Alter, A., 430

Alternative hypothesis, 110

Ampuero, J., 20

Anderson, C. L., 385

ANOVA (analysis of variance)

assumptions for, 277278

benefits of, 327328

between-groups

one-way, 277, 279298

two-way, 329, 337t, 340355

definition of, 276

F distributions and, 274279

factorial, 327

homoscedastic vs. heteroscedastic populations and, 278

notation for, 286

one-way, 273313. See also One-way ANOVA

terminology for, 277278, 327, 327t, 328329

3 × 2, 329

three-way, 327, 327t

two-way, 325355. See also Two-way ANOVA

within-groups

one-way, 277, 298308

two-way, 329

APA guidelines

for abbreviations, 8182

defaults and, 62

for statistical presentations, 223224, 256257

Archibold, R. C., 470

Arcidiacono, P., 20

Ariely, D., 360

Arithmetic operations, A–2

Armstrong, M. L., 56

Aron, A., 399

Aron, E. N., 399

Ashenfelter, O., 18

Assumptions, in hypothesis testing, 166167, 167t

Ayaz, H., 321

Azim, E., 264

Bailey, D. G., 327

Baird, M., 119

Baker, P., 390

Bang, H. M., 425

Banks, J., 389

Bar graphs, 5557, 56f58f, 67, 67f

for interactions, 334336, 334f, 335f, 338, 338f

Barac, R., 319

Bardwell, W. A., 241

Barkhorn, E., 359

Barr, A., 279, 297

Barran, R., 467

Barrett, C., 279, 297

Bartlett, C., 12

Bayer, P., 20

Bayramgurler, B., 467

Behenam, M., 182, 322

Bell curve. See Normal curve

Bellafante, G., 210

Bellosta, S., 328

Benbow, C. P., 186, 193, 204, 473

Bensinger, G., 415

Bernoulli, Daniel, 126

Bernstein, I. H., 407, 432

Bernstein, P. L., 377

Betts, N. M., 152

Between-groups ANOVA, 277

one-way, 277, 279298. See also One-way between-groups ANOVA

3 × 2, 329

two-way, 329, 337t, 340355. See also Two-way ANOVA, between-groups

Between-groups research design, 1213

Between-groups sum of squares

for one-way ANOVA, 289290, 289t, 290t, 302, 302t

for two-way ANOVA, 346t, 347348, 347t

Between-groups t test. See Independent-samples t test

Between-groups variance, 276277, 290

Bialystok, E., 319

Bias

confirmation, 105, 430

hindsight, 430

Biased sample, 49, 102103

Biased scale lie, 49

Bilton, N., 425

Bimodal distribution, 83, 83f

Bittman, Mark, 425

Blade of grass paradox, 106

Blatt, B., 121

Böckenholt, U., 200

Bok, D., 378

Bollinger, B., 170, 188

Bolyanatz, C., 279, 297

Boone, D. E., 181

Borsari, B., 123

Bos, M. W., 336, 338

Boulle, A., 153

Bowen, W. G., 378

Bradbury, T. N., 472

Brinn, D., 431

Bristol, Muriel, 158

Brody, H., 2

Brown, C. S., 271

Bruey, C., 12

Bryant, J., 24

Buchner, A., 203

Buckley, C., 105

Buckner, J. P., 44

Buekens, P., 332

Bukowski, W. M., 160, 163

Bunce, S., 321

Busseri, M. A., 320

Buxton, Laura, 105106

Calculators, statistical power, 203204

Callahan, Shannon, 418

Canadian Mental Health Association, 341

Carbonari, R., 274

Carey, K. B., 123

Carlin, J., 200

Causation, vs. correlation, 368

Ceiling effect, 37

Cells, in two-way ANOVA, 329, 329t, 336337, 337t

Centers for Disease Control and Prevention, 23

Central limit theorem, 139146

definition of, 139

distribution of means and, 139146

z scores and, 145146

Central tendency, 7886

definition of, 78

histograms and, 79f, 80

measures of

mean, 7981, 8485, 84f

median, 8182

mode, 8384

I-2

selection of, 8586

misleading use of, 86

outliers and, 8485, 84f, 86

SPSS and, 93

Chamarro, C., 474

Chance variability, 78

Chang, A., 271

Charles, C., 474

Chartjunk, 6162, 62f

Chi-square statistic, B–7

formula for, 437

for goodness of fit, 433, 434437, 435f, 435t

for independence, 440

Chi-square table, 435, 435t, B–7

Chi-square test, 432447

for goodness of fit, 433438

definition of, 432

formulas for, 434, 437

steps in, 433437, 460461

graphing percentages for, 444445, 445f, 445t

for independence, 438443

Cramer’s V for, 443444, 444t, 463

definition of, 432

effect size and, 443444, 444t

expected frequencies in, 440442, 442t

formulas for, 439, 441

steps in, 439443, 460461

relative risk and, 445446

SPSS and, 459460

Choma, B. L., 320

Claypool, H., 359

Coefficient alpha, 377

Cohen, J., 193, 203, 367, 443

Cohen’s conventions, for effect size, 262t, 294, 294t, 351, 351t

Cohen’s d, 196198, 197t

definition of, 196

formulas for, 196, 226, 234, 262

for independent-samples t test, 261262, 266

for paired-samples t test, 234

for single-sample t test, 225226

Coincidence, probability and, 106108

Cokely, E. T., 48

Coleman, C. D., 42

Combined effects. See Interactions

Comparison distributions, 168, 251t. See also Distribution(s)

Confidence intervals, 187191

calculation of, 188191, 204

definition of, 188

difference between means and, 258

formulas for, 190, 225, 233, 258259

for independent-samples t test, 258261, 259f, 260f, 266

interval estimates and, 187188

for paired-samples t test, 232234, 232f, 233f

point estimates and, 187

for single-sample t tests, 224225, 224f, 225f

upper and lower bounds of, 259

z distributions and, 188191

Confidence levels, 188

Confirmation bias, 105, 430

Confounding variables, 7

control of, 1012

Conley, C. A., 430

Contingency tables, 438439

Continuous observations, 56, 6t

Control groups, 110

Convenience sample, 100, 101, 102

Cooper, M. J., 426

Cornish, D. L., 390

Correlation, 10, 363390

characteristics of, 364367

definition of, 364

illusory, 105

meaning of, 364367

negative, 365, 367f, 371372

perfect, 366, 367f

positive, 365, 365f, 366f, 371372

perfect, 366, 366f

in psychometrics, 376378

reliability and, 376377

scatterplots for, 344346, 365, 365f367f, 370f, 374f

SPSS and, 380

strength of, 366367, 367t. See also Correlation coefficient

validity and, 377378

vs. causation, 368

vs. regression, 396, 406

Correlation coefficient, 364367, 380381

definition of, 364

formulas for, 372, 374375

magnitude of, 412

Pearson, 369375. See also Pearson correlation coefficient

in prediction, 394

proportionate reduction in error and, 411

Spearman rank-order, 449, 451453, 451t, B–10

strength of correlation and, 366367, 367t

vs. standardized regression coefficient, 402403

Correlational research, 10, 13

Corsi, A., 18

Corsini, A., 328

Cortina, J. M., 376, 377

Coulson, M., 191

Cox, R. H., 360

Coxcomb graph, 48, 48f, 59

Craik, F., 321

Cramer’s V (Cramer’s phi), 443444, 444t, 463

Cranor, L. F., 182

Critical region, 168

Critical values (cutoffs)

in hypothesis testing, 168, 173174, 173f

statistical power and, 200201

Cronbach’s alpha, 377

Cucchiara, A. J., 475

Cuddihy, L., 11

Cumming, G., 191192

Cunliffe, Stella, 248, 248f, 258

Cupples, A., 423

Cut-marks, 57

Cutoffs. See Critical values (cutoffs)

Czerwinski, M., 229, 232

Dahl, A. A., 17

Darlin, D., 415

Darwin, Charles, 407

Data sets, raw scores in, 25, 28

Davis, C. M., 270

De Moivre, Abraham, 126

De Morgan, Augustus, 126

Dean, G., 122

DeBroff, B. M., 322, 357

Decimals, A–3, A–5

Decker, B. P., 358

Deen, J. L., 20

Defaults, for graphs, 62

Degrees of freedom, 219221

between-groups

for one-way ANOVA, 281, 286

for two-way ANOVA, 343344

for chi-square test for goodness of fit, 434

for chi-square test for independence, 439

definition of, 219

formulas for. See Formula(s), for degrees of freedom

for independent-samples t test, 254

for Pearson correlation, 374375

for single-sample t test, 219221

total

for one-way ANOVA, 286

for two-way ANOVA, 343344

within-groups

for one-way ANOVA, 301

for two-way ANOVA, 344

Delucchi, K. L., 434

Deming, W. Edwards, 78

Dependent variables, 7, 12f, 6061

Descriptive statistics, 23

DeVellis, R. F., 376

Deviation(s)

ANOVA and, 286290

from the mean, 8889

squared, 89

standard. See Standard deviation

Diamond, M., 48

Dictator Game, 279280, 280f

Difference between means, confidence intervals and, 258

Dijksterhuis, A., 336, 338

Dinger, M. K., 214

Directional hypothesis, 171172

Discrete observations, 4, 6t

Distribution(s)

bimodal, 83, 83f

comparison, 168, 251t. See also Distribution of differences between means; Distribution of mean differences; Distribution of means

I-3

F, 274279

frequency, 2534. See also Frequency distributions

multimodal, 84f, 835

normal, 126129. See also Normal curve

overlap in, 284, 285f

skewed, 3637, 36f

t, 214219. See also t distributions

unimodal, 83

Distribution of differences between means, 248250, 251t

Distribution of mean differences, 227229, 228f, 251t

Distribution of means, 139140, 139146, 251t

characteristics of, 142145

creation of, 140142, 141f

definition of, 139140

effect size and, 194, 194f

spread of. See Standard error

standard deviation of, 142145, 143t, 144f

standard error and, 143145, 143t

vs. distribution of scores, 140142, 142145, 143t, 144f

z scores and, 144146

z table and, 164166

Ditto, P. H., 361

Donahue, W. M., 360

Doros, G., 390

Dorrington, R. E., 153

Dresser, G. K., 327

Dubner, S. J., 122, 155, 423, 433, 438

Ducks, 61

Duggan, M., 122

Dunn, C., 152

Ebbesen, E., 447

Eccles, J., 186, 187

Effect size, 194196

calculation of, 195196, 205

for chi-square test for independence, 443444

Cohen’s conventions for, 294, 294t, 351, 351t

Cohen’s d and, 196197, 197t. See also Cohen’s d

definition of, 194

distribution of means and, 194, 194f

for independent-samples t test, 261262, 266267

meta-analysis and, 197

for one-way between-groups ANOVA, 294, 294t

for one-way within-groups ANOVA, 306

for paired-samples t test, 234

proportionate reduction in error and, 408

sample size and, 194196, 194f, 195f

for single-sample t test, 225226

standard deviation and, 194, 194f, 196197, 197t

standard error and, 192193

for two-way ANOVA, 350351, 355

Effect sizes, Cohen’s conventions for, 262t

Eiser, C., 269

Ellison, N. B., 394

Engle-Friedman, M., 270

Ensign, W. Y., 241

Ensminger, J., 279, 297

Epidemiology, relative risk and, 445446

Equation(s). See also Formula(s)

for line, 398399, 399f

regression, 399402

Erdfelder, E., 203

η2 (eta squared), 294

Excel, for graph creation, G–1

Expected relative-frequency probability, 106107

Experiment(s). See also under Research

between-group design for, 1213

definition of, 11

random assignment in, 1112, 12f

vs. correlational studies, 10, 13

within-groups design for, 12, 13

Experimental groups, 110

External validity, 102

Extrapolation lie, 50

F distributions

for analyzing variability to compare means, 276277

in F table, 277, 282t, B–4

for three or more samples, 274279

vs. t distributions, 275, 277, 277t

vs. z distributions, 275, 277, 277t

F statistic

definition of, 276

in one-way ANOVA, 275276

between-groups vs. within-groups variance and, 284

calculation of, 276

formulas for, 290, 304

logic of, 283286, 285f

source table for, 285286, 286t, 290, 291t, 302304, 302t304t

in two-way ANOVA, 329330

F table, 282283, 282t, B–4

for analyzing variability to compare means, 276277

vs. t table, 277

Fackler, M., 183

Factorial ANOVA, 327

Factors, 327

Fallow, G. O., 72

Fallows, James, 299, 307

Fan, J., 245, 268

Faul, F., 203

Federmeier, K. D., 430

Feng, J., 12

Fennema, E., 187

Fidler, F., 191

Fields, D. A., 214

Figures. See Graphs

Finkelsteine, S., 361

Fishbach, A., 361

Fisher, A., 243

Fisher, R. A., 158

Fleisher, B. M., 470

Floor effect, 36

Flynn, C., 386, 423

Follow-up tests, 295

Fong, K. N. K., 475

Formula(s)

for between-groups variance, 290

for chi-square statistic, 437

for Cohen’s d, 196, 262

for independent-samples t test, 262

for paired-samples t test, 234

for single-sample t test, 226

for confidence intervals

for independent-samples t test, 258259

for paired-samples t test, 233

for single-sample t tests, 225

with z distribution, 190

for correlation coefficient, 372, 374375

for Cramer’s V, 443

for degrees of freedom

for chi-square test for goodness of fit, 434

for chi-square test for independence, 439

for independent-samples t test, 254

for one-way between-groups ANOVA, 281, 286

for one-way within-groups ANOVA, 281, 301

for single-sample t test, 219

total, 286, 344

for two-way between-groups ANOVA, 343344

for two-way within-groups ANOVA, 344

for distribution of differences between means, 255

for effect size

for one-way between-groups ANOVA, 294

for one-way within-groups ANOVA, 306

for two-way ANOVA, 350351

for expected frequencies, for chi-square test, 441

for F statistic, 290, 304

for grand mean, 287

for harmonic mean, 296

for independent-samples t test, 254256

for Mann-Whitney U test, 456

for mean, 8081

for mean squares, 304, 349

for Pearson correlation, 374375

for pooled variance, 254

for probability, 107

for proportionate reduction in error, 411

for range, 8788

I-4

for simple linear regression, 396, 398, 402

for Spearman rank-order correlation coefficient, 453

for standard deviation, 90

of distribution of differences between means, 255

estimated from sample, 215

for standard error, 143144

estimated from sample, 217

using N′, 295296

for standardized regression coefficient, 402

standardized regression equation, 396

for sum of squares

between-groups, 289, 346348

subject, 303304

total, 287288, 290, 345

within-groups, 288, 303304, 348

for t statistic, 218

for independent-samples t test, 254256

for single-sample t test, 226

for Tukey HSD test, 295296

for variance, 90

of distribution of differences between means, 255

within-groups, 290

for z scores, 132, 134, 145

Fosse, E., 244

Fox, J. R., 316

Fractions, A–3, A–4, A–5

Frequency distributions, 2534

definition of, 25

frequency tables and, 2533, 26t, 28t

histograms and, 3033, 31f, 32f

normal, 35–36, 36f

shapes of, 3537

skewed, 3637, 36f

SPSS and, 38

Frequency polygons, 3334, 33f, 3940

Frequency tables, 2533, 26t, 28t

construction of, 2728, 39

definition of, 25

grouped, 2830, 30t

SPSS and, 38–39

Friedler, Shevach, 431

Friendly, Michael, 48

Funder, D. C., 187

Fung, C. M., 160, 163

Gailliot, M. T., 60

Galinksy, A. D., 360

Gallagher, M. W., 63

Gallagher, R. P., 145

Galton, Francis, 407, 432

Garb, H. N., 8

Garber, J., 386, 423

Garcia-Retamero, R., 48

Gaspar, J. G., 274

Geier, A. B., 390

Gelman, A., 4, 200

Generalizability, 102

Gentile, D. A., 11

Geographic information systems, 63

Georgiou, C. C., 152

Gilbreth, F., 100

Gilbreth, L., 100

Gill, G., 48

Gilovich, T., 74, 430

Golan, R., 270

Goldenberg, D., 43

Golder, S. A., 54

Gonnerman, Jr., M. E., 390

Gonzalez, G., 215, 279

Goodman, A., 19, 425

Gordon, A. M., 385

Gossett, W. S., 139

G*Power, 203204

Graepel, T., 388

Grand mean, 287, 289, 289t, 290

Graphs

bar, 5557, 56f58f, 67, 67f

for interactions, 334336, 334f, 335f, 338, 338f

chartjunk in, 6162, 62f

construction of, 6162

coxcomb, 48, 48f, 59

creating with Excel, G–1

extrapolation and, 50

faults for, 62

frequency polygons, 3334, 33f, 3940

geographic information systems and, 63

histograms, 3033, 31f, 32f, 39, 79f, 80, 448, 449f

historical perspective on, 48, 48f

how to read, 6061

interpolation and, 49, 49f

line, 5355, 54f, 55f

vs. bar graphs, 336

misleading, 48–50, 5657

mutivariable, 6364, 63f

Pareto charts, 55, 56f

pictorial, 5758, 58f

pie charts, 58, 58f

range-frames, 52, 52f

scatterplots, 5153, 6667, 67f

for correlation, 344346, 365, 365f367f, 370, 370f, 374f

line of best fit in, 53, 54f, 401402, 402f

selection of, 59

SPSS and, 6566

time plots, 54

types of, 5158

Greaves, E., 19, 425

Grids, 61

Grimberg, A., 475

Griner, D., 210

Gross, N., 244

Grouped frequency tables, 2830, 30t

Guéguen, N., 76, 471

Gulen, H., 426

Hannan, M. T., 423

Harding, Kate, 469

Hardy, Q., 97

Harmonic mean, 296

Harris, J., 215, 279

Harris, R. J., 12

Harton, H. C., 358

Harville, E., 332

Hashimoto, M., 470

Hatchett, G. T., 88, 199, 221

Hatfield, E., 389

Haug, T. T., 17

Hays, W. L., 345

Healey, J. R., 387

Healey, M., 191

Healy, J., 24

Heatherton, T. F., 227

Hendriks, T., 321

Henrich, J., 279, 297

Hershfield, H. E., 425

Herszenhorn, D. M., 376

Heteroscedastic populations, 278

Heyman, J., 360

Highfield, R., 121

Hindsight bias, 430

Hinton, P. S., 360

Histograms, 3033, 31f, 32f, 39, 448, 449f

central tendency and, 79f, 80

Hizmo, A., 20

Hockenbury, D. H., 208

Hockenbury, S. E., 208

Hoerr, S. L., 152

Hoffmann, C. J., 153

Holiday, A., 386

Hollon, S. D., 293

Holm-Denoma, J. M., 227

Homogeneity of variance, 278

Homoscedastic populations, 278

Honegger, S. D., 70

Hoxby, C., 211

Hugenberg, K., 359

Hull, H. R., 214

Huwe, J. M., 72

Hyde, J. S., 187, 194

Hypothesis

alternative, 110

development of, 110

directional, 171172

nondirectional, 172

null, 110, 168

notation for, 172

rejection vs. failure to reject, 111112, 112t

Type I/II errors and, 113114

research, 110, 168

direction of, 171172

notation for, 172

robust, 167

Hypothesis test, 170175

robust, 167

Hypothesis testing, 913, 111112, 112t, 166178. See also specific methods

ANOVA in. See ANOVA (analysis of variance)

assumptions in, 166167, 167t

I-5

between-groups vs. within-groups design in, 1213

comparison distributions in, 168, 251252, 251t

confounding variables in, 1012

correlational research in, 10, 13

critical values in, 168, 173174, 173f

definition of, 9

directionality in, 171172

example of, 170175

experiments in, 1013

independent-samples t test in, 247267

limitations of, 186187

meta-analysis in, 197

nonparametric tests in, 167

null hypothesis in, 168

one-tailed tests in, 172, 201202, 202f

p levels (alphas) in, 168

paired-samples t test in, 226234

parametric tests in, 167

populations in, 167, 168

post hoc tests in, 295298, 345

regression in, 402403

reporting results of, APA guidelines for, 223224, 256257, F–1

research hypothesis in, 168

robust tests in, 167

single-sample t test in, 219226

SPSS and, 176

statistical significance in, 168

steps in, 167169, 169t

test statistic in, 168, 174

Tukey HSD test in, 295297, 306307

two-tailed tests in, 172, 201202, 202f

Type I errors and, 113

Type II errors and, 113114

z table in, 158166

Illusory correlation, 105

IMD International, 451

Inaccurate values lie, 50, 50f

Independence, probability and, 108

Independent trials, 108

Independent variables, 7, 12f, 6061, 60f

combined effects of, 326327

interactions and, 326327, 330340, 330t

Independent-samples t test, 248267

Cohen’s d for, 261262, 266

confidence interval for, 258261, 259f, 260f, 266

definition of, 248

distribution of differences between means and, 248250, 251t

effect size for, 261262, 266267

formulas for, 254256

nonparametric equivalent for, 449, 449t, 453456

pooled variance and, 254

steps in, 250256, 264265

Indiana University Media Relations, 316

Inferential statistics, 3, 109113

Interactions, 326327, 330340, 330t, 345350

bar graphs for, 334336, 334f, 335f, 338, 338f

definition of, 326327

interpretation of, 332338

public policy and, 331332

qualitative, 332, 336338, 338f, 349f, 350

quantitative, 332336, 334f, 335f

Intercept, 398400, 399f, 414, 414f

Interpolation lie, 49, 49f

Interval estimates, 187188. See also Confidence intervals

Interval midpoints, 3233

Interval variables, 5, 6t

Irwin, M. L., 311, 317

Izzetoglu, K., 321

Jacob, C., 76, 471

Jacob, J. E., 186, 187

Jacobs, T., 57

Jefferson, A. D., 270

Jo, B., 264

John-Henderson, N., 385

Johnson, L. F., 153

Johnson, W. B., 72

Joiner, T. E., 227

Kaczmarski, H., 274

Karahalli, E., 467

Karney, B. R., 472

Keim, K., 152

Keiser, O., 153

Kell, H. J., 473

Kelly, I. W., 122

Keltner, D., 385

Kennedy, S. H., 197

Kida, T., 430

Kiel, D. P., 423

Kim, K., 9, 270

Kim, S., 447, 450, 451, 453, 456, 457

Klonsky, J., 11

Koch, C., 72

Koch, J. R., 56

Koehler, J. J., 430

Kominski, R., 42

Kosinski, M., 388

Krahé, B., 13

Kramer, A. F., 274

Krugman, P., 385, 389

Krulwich, R., 105

Kruskal-Wallis H test, 449, 449t

Kuck, V. J., 44

Kuo, C., 182

Kuper, S., 25

Kutikov, J. K., 475

LaCroix, R., 311, 317

Lam, R. W., 197

Lambert, J., 75

Lamon, S. J., 187

Lampe, C., 394

Lamy, L., 76, 471

Landrum, E., 277

Lauer, J. B., 380

Lavner, J. A., 472

Law of large numbers, 108

Lee, Y. T., 44

Lee, Y.-J., 364

Leibbrandt, A., 470

Leslie, P., 170, 188

Leung, D. P. K., 475

Levels, 7

Levine, J. M., 187

Levitt, S. D., 122, 155, 423, 433, 438

Lilienfeld, S. O., 8

Line

equation for, 398, 399f

regression, 400402, 401f

Line graphs, 5355, 54f, 55f

vs. bar graphs, 336

Line of best fit, 53, 54f, 401402, 402f

standard error of the estimate and, 405406, 406f

Linear regression. See Regression

Linear relationship, 53

List, J. A., 470

Lloyd, C., 471

Loeb, S., 97

Longitudinal studies, 13

Lopez, D. L., 361

Lopez, J. J., 63

Loschelder, D. D., 360

Lower bound, of confidence interval, 259

Lubinski, D., 473

Lucas, M. E. S., 20

Luo, L., 321

Lutz, G. M., 390

Lynch, P. J., 11

Ma, J., 244

Mackie, D. M., 187

Macy, M. W., 54

Main effect, 326, 329330, 330t, 333, 333t

marginal means and, 333, 333t, 336337, 337t

Major, D., 270

Maks, S. P., 432

Malpass, R. S., 447

Maner, J. K., 60

Mann-Whitney U test, 449, 449t, 453456, 455t, 464466

SPSS and, 459460

Marginal mean, 333, 333t, 337338, 337t

Mark, G., 215, 279

Markoff, J., 63

Markowitz, J. C., 293

Marmot, M., 389

Marzabadi, C. H., 44

Massey, A., 385

Mathewson, K., 274

Mayer, J., 214

Mazer, J. P., 319

I-6

McCann, A., 83

McCollum, J. F., 24

McElreath, R., 279, 297

McGivern, J. L., 70

McNeil, G. D., 385

McShane, B. B., 200

McVarish, L., 311, 317

Mean(s), 7981

calculation of, 7980, 8081, 9394

confidence intervals and, 188, 258259.See also Confidence intervals

definition of, 79

deviation from, 8889

distribution of, 139146. See also Distribution of means

formula for, 8081

grand, 287, 289, 289t, 290

harmonic, 296

marginal, 333, 333t, 337338, 337t

notation for, 8081, 80t

outliers and, 8485, 84f, 86

as point estimates, 187

sample, 142, 216, 289t, 290

squared deviations from, in source tables, 285286, 286t

visual representations of, 80

vs. median, 85

when to use, 85

z scores and, 130131, 131f

Mean differences, distribution of, 227229, 228f

Mean squares, 89

formulas for, 304, 349

Mecklenburg, S. H., 447

Median, 8182

calculation of, 8182, 9394

definition of, 81

outliers and, 8485

vs. mean, 85

Medvec, V. H., 74

Mehl, M. R., 268

Menon, V., 264

Merrell, R., 11

Meta-analysis, 197

Metzner, B. S., 380

Meyer, Urban, 432

Midpoints, of intervals, 3233

Milczarski, W., 469

Miller, D. T., 358

Miller, J., 359

Miller, S. L., 60

Mills, P. J., 241

Mitchell, P., 327

Mobbs, D., 264

Mode, 8384, 8586

calculation of, 93

Moiré vibrations, 61, 62f

Möller, I., 13

Morawski, S., 9, 270

Morf, C. C., 187

Morita, K., 423

Mossong, J., 153

Mueller, P. A., 271, 323

Multimodal distribution, 83, 84f

Multiple regression, 413416, 414f, 414t

definition of, 413

in everyday life, 415

regression equation for, 413415

Multivariable graphs, 6364, 63f

Munro, G., 123

Munro, J., 123

Murphy, K. R., 199

Murphy, R. E., 319

Myers, B., 229, 232

Mykletun, A., 17

Myors, B., 199

Nail, P. R., 358

Negative correlation, 365, 366f, 371372

perfect, 366, 367f

Negatively skewed distribution, 36f, 37

Neighbors, L., 243

Newman, Andy, 385

Newton, R. R., 197, 332

Nezworski, M. T., 8

Ng, A. K. Y., 475

Nicol, Adelheid, 48

Nightingale, Florence, 48, 59

Nolan, S. A., 44, 386, 423

Noll, R. B., 160, 163

Nominal variables, 4, 6t, 430t, 431

Nondirectional hypothesis, 172

Nonlinear relationship, 53, 54f

Nonparametric statistics, 167, 430431

Nonparametric tests, 167, 429477

chi-square, 432447

equivalent parametric tests for, 449450, 449t

Kruskal-Wallis W test, 449, 449t

Mann-Whitney U test, 449, 449t, 453456, 455t, 459460, 464466

for ordinal data, 449f, 449t, 448456

Spearman rank-order correlation coefficient, 448, 449t, 451453

SPSS and, 459460

when to use, 431, 450

Wilcoxon signed-rank, 449, 449t, B–13

Nordgren, L. F., 336, 338

Normal curve, 126129, 126f

central limit theorem and, 139146

definition of, 126

distribution of means and, 139146

percentages and, 137138, 138f

sample size and, 127138, 127f, 128f, 128t,

SPSS and, 147148

standardization and, 129139

z scores and, 130139, 158166

Normal distribution, 35–36, 36f

assumption of, 167

standard, 135

Notation, A–2

for ANOVA, 286

capitalization in, 81

italics in, 81

for mean, 8081, 80t

for null hypothesis, 172

for Pearson correlation coefficient, 369

for research hypothesis, 172

for standard deviation, 89, 90, 90t, 215

for standard error, 143

Nouven, T. T., 214

Null hypothesis, 110, 168

notation for, 172

rejection vs. failure to reject, 111112, 112t

Type I/II errors and, 113114

Numbeo, 241

Nunnally, J. C., 376

Nunziata, R., 42

Oberst, U., 474

Observations

continuous, 56, 6t

discrete, 4, 6t

O’Doherty, J., 250

Ogbu, J. U., 208

Oldfield, Z., 389

Onaral, B., 321

O’Neil, P. M., 214

One-tailed test, 172

statistical power and, 201202, 202f

One-way ANOVA, 273313

assumptions for, 277278

definition of, 277

notation for, 286

terminology of, 277278

vs. two-way ANOVA, 328, 340

One-way between-groups ANOVA, 277, 279298

effect size (R2) for, 294

F statistic and, 283290. See also F statistic

formulas for, 281, 286, 294

nonparametric equivalent for, 449, 449t

post hoc tests for, 295298

quantifying overlap with, 284, 285f

source tables and, 285286, 286t, 290, 291t

SPSS and, 310311

steps in, 280283, 291292, 311313

sums of squares and, 286290, 288t291t

Tukey HSD test for, 295297

One-way within-groups ANOVA, 277, 298308

benefits of, 299300

formulas for, 281282, 301, 303304, 306

SPSS and, 310311

steps in, 300304

sum of squares and, 286290, 288t, 289t, 290t, 300304, 302t304t

Tukey HSD test for, 306307

Operational definition, 10, 10t

Operationalized variables, 10, 10t

Oppenheimer, D., 271, 323, 430

I-7

Ord, T., 20

Order of operations, A–3

Ordinal data, 448456

correlation and, 448456

nonparametric tests for, 448456, 449t

transforming scale data to, 451452

Ordinal variables, 5, 6t, 431

distribution of, 449, 449f

Spearman rank-order correlation coefficient for, 449, 449t, 451453

Orthogonal variables, 413

Outcome, 107

Outliers, central tendency and, 8485, 84f, 86

Ovtchinnikov, A. V., 426

Owens, D., 56

p levels (alphas), 168, 201, 201f

Pahk, P. J., 322, 357

Paired-samples t test, 214, 226234, 251t

Cohen’s d for, 234

confidence interval for, 232234, 232f, 233f

definition of, 227

effect size for, 234

nonparametric equivalent for, 449, 449t

SPSS and, 236

steps in, 229232, 237

Palazzo, D. J., 364

Paller, K. A., 430

Paneth, N., 2

Paoletti, R., 328

Parameters, 80, 80t

Parametric tests, 167

equivalent nonparametric tests for, 449450, 449t

Pareto charts, 55, 56f, 68, 68f

Park, D. C., 340, 341

Parker-Pope, T., 389

Pearson correlation coefficient, 369375, 370t, B–9

calculation of, 369373, 372t, 381382

definition of, 369

hypothesis testing with, 373375

nonparametric equivalent for, 449, 451453, 452t

notation for, 369

standardized regression equation and, 395396

Peebles, D., 336

Pennebaker, J. W., 268

Percentages, A–3, A–5

normal curve and, 137138, 138f

vs. probability, 107

z table and, 158164

Percentiles, transforming z scores into, 135, 137138, 160161, 161f, 162, 175f, 177

Personal probability, 106

Peters, P. K., 152

Petrocelli, J. V., 208, 422

Pexman, Penny, 48

Pictorial graphs, 5758, 58f

Pie charts, 58, 58f

Pinto, J. N., 322

Plassmann, H., 250

Point estimates, 187

Pooled standard deviation, 261

Pooled variance, 254, 261

Pooya, O., 182, 322

Popkin, S. J., 269

Population, 3

heteroscedastic, 278

homoscedastic, 278

standard deviation of

estimation from sample, 215217

standard error and, 143145

variance of, 89. See also Variance

vs. sample, 3

Positive correlation, 365, 365f, 366f, 371372

perfect, 366, 366f

Positively skewed distribution, 36, 36f

Posner, M. L., 245, 268

Post hoc tests, 295298, 345

Postman, N., 25

Power. See Statistical power

Pratt, J., 12

Prediction

correlation coefficient in, 394

errors in, 405412

regression in. See Regression

vs. relation, 395

Press, E., 471

Pressman, S. D., 63

Pritchard, D. E., 364

Probability, 105112

calculation of, 117

coincidence and, 106108

definition of, 106

expected relative-frequency, 106107

formula for, 107

independence and, 108

personal, 106

SPSS and, 116

vs. percentage, 107

vs. proportion, 107

Proportionate reduction in error

for multiple regression, 415

for simple linear regression, 408412

Proportions, A–3

Psychometricians, 376

Psychometrics, 376378

reliability and, 376377

validity and, 377378

Puri, M., 20

q table

for between-groups ANOVA, 297298, 297t

for within-groups ANOVA, 307

q test (Tukey HSD test), 295297, 306307, B–8

Qiao, N., 423

Qualitative interactions, 332, 336338, 338f, 349f, 350

Quantitative interactions, 332336

Quaranta, A., 321

Quinn, D. M., 14

R2. See also Effect size

definition of, 294

for one-way between-groups ANOVA, 294, 294t

for one-way within-groups ANOVA, 306

for two-way ANOVA, 350351, 351t, 355

r2 (proportionate reduction in error), 411

Rachman, S., 2

Radley, D., 214

Rajan, B., 311, 317

Rajecki, D. W., 380

Ralston, M., 390

Ramirez-Esparza, N., 268

Random assignment, 1112, 12f, 103104

Random numbers generator, 101

Random numbers table, 101, 101t

Random sample, 100101

Random selection, 103, 116117

assumption of, 167

Range, 8788

Range-frames, 52, 52f

Rangel, A., 250

Ranking, ordinal variables in, 5, 6t

Rating scales, biased, 49

Ratio variables, 5, 6t

Ratner, R. K., 358

Raw scores

conversion to z scores, 130133, 131f, 158164, 162, 177

definition of, 25

distribution of, vs. distribution of means, 140142, 142145, 143t, 144f

in frequency tables, 2533

z score conversion to, 134136

z table and, 158164

Raz, A., 245, 268

Regan, T., 229, 232

Regression, 393427

benefits of, 395

interpretation in, 405412

limitations of, 406

multiple, 413416, 414f, 414t

predictive accuracy with, 405412

proportionate reduction in error and, 408412

simple linear, 394405

definition of, 395

equation for, 398402

formulas for, 396, 398, 402

hypothesis-testing with, 402403

line of best fit in, 53, 54f, 401402, 402f, 405406, 406f

with raw scores, 419

regression to the mean and, 397, 397t, 407, 407t

I-8

slope and intercept in, 398400, 399f, 401402

standardized regression equation for, 396, 402403, 403t

with z scores, 396398, 397t, 418419

sources of error in, 405412

SPSS and, 418

standard error of the estimate and, 405406, 406f, 408

vs. correlation, 395, 406

Regression coefficient, standardized, 402403, 403t

Regression equation

for multiple regression, 413415

proportionate reduction in error and, 408, 411, 415

for simple linear regression, 399402

standardized, 396

Regression line, 400402, 401f

Regression to the mean, 397, 397t, 407, 407t

Reiss, A. L., 264

Relative risk, 445446

Reliability, 8, 376377

Repeated-measures ANOVA. See One-way within-groups ANOVA

Repeated-measures research design, 12, 13

Replication, 102

Reports, statistical, APA guidelines for, 223224, 256257, F–1

Research designs

between-group, 1213

correlational, 10, 13

with nominal independent and dependent variables, 430t. See also Chi-square test

with scale independent and dependent variables, 430t

within-groups, 12, 13

Research hypothesis, 110, 168

direction of, 171172

notation for, 172

Reynolds, G., 385

Richards, S. E., 471

Riela, S., 270

Rip, M., 2

Roach, William, 158

Roberts, A. E., 56

Roberts, P. M., 205, 206

Roberts, S. B., 214

Robertson, G., 229, 232

Robust hypothesis tests, 167

Rockwell, P., 431

Romanosky, S., 182

Rorschach inkblot test, 8, 8f

Rosario, F., 106

Rosenberg, T., 20

Rosenthal, R., 197

Rosser, J. C., 11

Rouby, D. A., 60

Rounding off, 2728

Rozin, P., 390

Rubin, D. C., 269

Ruby, C., 317

Rudestam, K. E., 197, 332

Ruhm, Christopher, 395, 407

Ryan, C., 431, 438

Ryan, E. G., 18

Sadava, S. W., 320

Sample

biased, 49, 102103

convenience, 100, 101, 102

definition of, 3

estimation of standard deviation from, 215217

estimation of standard error from, 217

random, 100101

self-selected, 102

variance of, 89. See also Variance

volunteer, 102

vs. population, 3

Sample mean, 142, 289t, 290

calculation of, 216

Sample size

effect size and, 194196, 194f, 195f

normal curve and, 127138, 127f, 128f, 128t

statistical power and, 202, 202f, 203

statistical significance and, 192193

t distributions and, 214215, 215f, 219220

Sampling

with replacement, 140

SPSS and, 116

Sandberg, D. E., 160, 163

Sandhofer, C. M., 271

Scale data, transforming to ordinal data, 451452

Scale variables, 6, 430t

Scatterplots, 5153, 6667, 67f

for correlation, 344346, 365, 365f367f, 370, 370f, 374f

line of best fit in, 53, 54f, 401402, 402f

Schaller, B., 385

Schmidt, M. E., 24

Schomaker, M., 153

Schwarz, N., 340, 341

Scores. See Raw scores; z score(s)

Sebring, N. G. A., 214

Self-selected sample, 102

Seymour, C., calculation of, 369373

Sherman, J. D., 70

Shewokis, P. A., 321

Shiv, B., 250

Silver, N., 83

Simonds, C. J., 319

Simple linear regression. See Regression, simple linear

Single-sample t test, 219226, 251t

Cohen’s d for, 225226

confidence intervals for, 224225, 224f, 225f

definition of, 219

degrees of freedom for, 219221

effect size for, 225226

SPSS and, 236

steps in, 221223, 223f, 237

vs. z test, 214215

Siniscalchi, M., 321

Skewed distribution, 36, 36f

Skurnik, I., 340, 341

Slatcher, R. B., 268

Slope, 398400, 399f, 402403

Smith, G., 229, 232

Smith, J. P., 389

Smith, T. B., 210

Smith, T. W., 448, 450, 451, 453, 456, 457

Sneaky sample lie, 49

Snow, John, 2, 3, 9, 13, 63, 364, 445

Sobal, J., 243

Social capital, 394

Sorenson, A., 170, 188

Source tables

definition of, 285

expanded, 330t, 349t

for one-way ANOVA

between-groups, 285286, 286t, 290, 291t

within-groups, 302304, 302t304t

for two-way ANOVA, 330, 330t, 348349, 349t

Sovik, K. N., 214

Spearman rank-order correlation coefficient, 449, 451453, 451t, B–10

Spence, I., 12

Spencer, S. J., 14

Split-half reliability, 377

Spread. See Standard deviation; Standard error

Sprecher, S., 389

SPSS (Statistical Package for the Social Sciences)

central tendency, 93

chi-square test, 459460

correlation, 380

Data View, 15

frequency polygons, 3940

frequency tables, 38–39

graphs, 6566

histograms, 39

hypothesis testing, 176

for independent-samples t test, 263264

Mann-Whitney U test, 459460

nonparametric tests, 459460

one-way ANOVA, 310311

paired-samples t test, 236

probability, 116

regression, 418

sampling, 116

scale variables, 15

single-sample t test, 236

two-way ANOVA, 353

variability, 93

Variable View, 15

z tests, 176

Squared deviations, 89

from the mean, in source tables, 286290, 286t

mean of. See Standard deviation

sums of, 286290

Stampone, E., 6

Standard deviation, 90

I-9

calculation of, 90, 94

definition of, 90

of distribution of means, 142144, 143t, 144f

effect size and, 194, 194f, 196197, 197t

formulas for, 90, 215

notation for, 89, 90, 90t, 215

pooled, 261

of population

estimation from sample, 215217

standard error and, 143145

squared, 8990, 286290

statistical power and, 202f, 203

z scores and, 130131

Standard error, 143145, 143t

definition of, 143

effect size and, 192193

of the estimate, 405406, 406f, 408

formulas for, 143144, 217, 296

notation for, 143

sample size and, 192193

for t statistic, 217218

z scores and, 145

Standard normal distribution, 135

Standardization, 129139

definition of, 129130

need for, 130

z scores in, 130139, 131f. See also z score(s)

Standardized regression coefficient, 402403, 403t

Standardized regression equation, 396

Stanley, J. C., 186, 193, 204

Starkweather, G., 229, 232

Statistic

definition of, 80

vs. parameter, 80, 80t, 81f

Statistical assumptions, in hypothesis testing, 166167, 167t

Statistical Package for the Social Sciences. See SPSS (Statistical Package for the Social Sciences)

Statistical power, 198204

calculation of, 199201, 199t, 203204

critical values and, 200201

definition of, 198

importance of, 199201

variables affecting, 201204, 201f203f, 202f

Statistical prediction

correlation coefficient in, 394

regression in, 394395. See also Regression

vs. relation, 395

Statistical presentations, APA guidelines for, 223224, 256257, F–1

Statistical significance, 168

practical importance of, 193

sample size and, 192193

Statistical tests. See Test(s)

Statistics

descriptive, 23

inferential, 3, 109113

misuse of, 48–50

nonparametric, 167, 430431

parametric, 167

Steele, C. M., 14

Steele, J. P., 322

Steinfeld, C., 394

Steinman, Gary, 460

Stellar, J. E., 385

Ste-Marie, D. M., 270

Stewart, B., 152

Stigler, S. M., 116117, 139

Stillwell, D., 388

Stone, M., 48

Street, W. N., 274

Stroop test, 5, 5f

Subject sum of squares, 301, 303304, 303t

Success, 107

Sum of squares, 89, 286290

between-groups

for one-way ANOVA, 289290, 289t, 290t, 302, 302t

for two-way ANOVA, 346348, 346t, 347t

in regression, 402403, 403t

in source tables, 286290, 286t

subject, 301, 303304, 303t

total

for one-way ANOVA, 286290, 288t, 290, 290t, 301302, 302t

for two-way ANOVA, 345, 346t

within-groups

for one-way ANOVA, 286290, 288t, 290t, 300304, 302t304t, 303t

for two-way ANOVA, 348, 348t

Sutherland, A., 106

Swabb, R. I., 360

Symbolic notation. See Notation

Szymanski, S., 25

t distributions, 214219

in calculating standard error, 217218

in calculating t statistic, 218

in estimating standard deviation from sample, 215217

sample size and, 214215, 215f

spread of, 215, 215f

in t table, 219221, 220t

vs. F distributions, 275, 277, 277t

vs. z distributions, 214215, 215f

t statistic

calculation of, 218

Cohen’s d for, 225226

definition of, 218

formulas for, 218, 226, 254

for independent-samples t test, 254

standard error for, calculation of, 217218

vs. z statistic, 218, 220

t table, 219221, 220t

vs. F table, 277

t tests. See also Independent-samples t test; Paired-samples t test; Single-sample t test

comparison distributions for, 251t

F table as, 277

selection of, 251t

Type I errors with, 275

Tal, A., 271

Talarico, J. M., 269

Taylor, G. M., 270

Test(s)

nonparametric, 167, 429477. See also Nonparametric tests

parametric, 167

equivalent nonparametric tests for, 449450, 449t

selecting, E–1

Test statistic

calculation of, 168, 174

F. See F statistic

sample size and, 192193

t. See t statistic

z. See z statistic

Test-retest reliability, 376

Thase, M. E., 293

Thomas, T. R., 360

3 × 2 ANOVA, 329

Three-way ANOVA, 327, 327t

Tierney, John, 109, 110, 112

Time plot, 54

Time series plot, 54

Total degrees of freedom

for one-way ANOVA, 286

for two-way ANOVA, 344

Total sum of squares

for one-way between-groups ANOVA, 287288, 288t, 290, 290t

for one-way within-groups ANOVA, 301302, 302t

for two-way between-groups ANOVA, 346, 346t

Trials. See also Experiment(s)

definition of, 107

outcome of, 107

success of, 107

Trötschel, R., 360

Tuckel, P., 469

Tucker, K. L., 423

Tufte, Edward, 52, 57, 58, 61

Tukey HSD test, 295297, 306307, B–8

Turner, S., 211

Tversky, A., 430

Tversky, B., 336

Tworoger, S. S., 311, 317

Two-tailed test, 172

statistical power and, 201202, 202f

Two-way ANOVA, 325355

benefits of, 327328

between-groups, 327, 329, 337t, 340352

effect size for, 350351, 355

sources of variability in, 345350

SPSS and, 353

steps in, 341345, 354355

cells in, 329, 329t, 337338, 337t

definition of, 327

F statistic in, 329330

factorial, 327

formulas for, 343344, 346350

interactions in, 326327, 330340, 330t. See also Interactions

I-10

main effects in, 326, 329330, 333, 333t

marginal means in, 333, 333t, 337338, 337t

mixed design, 327

source tables for, 330, 330t, 348349, 349t

sum of squares for, 346348, 346t, 347t, 348t

terminology for, 327, 328329, 337t

vs. one-way ANOVA, 328, 340

within-groups, 329, 344

Type I errors, 113

with t tests, 275

with three or more comparisons, 275, 275t

Type II errors, 113114

Unimodal distribution, 83

Unutmaz, S., 467

Upper bound, of confidence interval, 259

Upton, P., 269

Usher, A., 75

Uskul, T. B., 467

Validity, 8, 377378

external, 102

Vallone, R., 430

Vallortigara, G., 321

Van Baaren, R. B., 336, 338

Vandewater, E. A., 24

Vann Ittersum, K., 272

Variability

central tendency and, 7886

chance, 78

definition of, 87

measures of, 78, 8790

range, 8788

variance, 8890

SPSS and, 93

Variables, 45

confounding, 7, 1012

correlation between, 10

definition of, 4

dependent, 7, 12f, 6061

independent, 7, 12f, 6061, 60f

combined effects of, 326327. See also Interactions

interactions and, 326327, 330340, 330t

interval, 5, 6t

levels of, 7

linear/nonlinear relationship between, 53, 54f

nominal, 4, 6t, 430t, 431

operationalized, 10, 10t

ordinal, 5, 6t, 431, 448456

distribution of, 449, 449f

Spearman rank-order correlation coefficient for, 449, 449t, 451453

orthogonal, 413

ratio, 5, 6t

reliability of, 8

scale, 6, 430t

single unknown, solving equations with, A–6

validity of, 8

Variance, 8890

between-groups, 276277, 290

calculation of, 101

formulas for, 90, 254255

homogeneity of, 278

notation for, 89, 90t

pooled, 254, 261

of population, 89, 90t

R2 and, 294, 294t

of sample, 89, 90t

square root of. See Standard deviation

within-groups, 276277, 290

Vazire, S., 187, 268

Ventuneac, A. M., 270

Vinten-Johansen, P., 2

Visual displays. See Graphs

Vohs, K. D., 227

Voichick, J., 152

Volunteer sample, 102

Von Seidlein, L., 20

Voss, J. L., 430

Walker, S., 211, 473

Wang, X., 20

Wansink, B., 271, 272

Ward, M., 182

Warnakulasooriya, R., 364

Waters, Alice, 271

Weber, E. U., 425

Weinberg, B. A., 470

West, S. G., 187

Wilcoxon signed-rank test, 449, 449t, B–13

Wiley, J., 270

Willems, B., 321

Windsor, M. B., 274

Within-groups ANOVA, 277

one-way, 277, 298308. See also One-way within-groups ANOVA

two-way, 329

Within-groups research design, 12, 13

Within-groups sum of squares

for one-way ANOVA, 288289, 288t, 290t, 300304, 302t304t, 303t

for two-way ANOVA, 348, 348t

Within-groups variance, 276277, 290

Wolff, A., 413

Wood, J. M., 8

Woodley, W., 269

Word, D. L., 42

World Health Organization, 341

Xiong, X., 332

Yanovski, J. A., 214

Yanovski, S. Z., 214

Yasui, Y., 311, 317

Yerkes-Dodson law, 53, 54f

Yilmaz, A., 467

Yoon, C., 340, 341

York, B. N., 97

z distribution(s), 135

confidence intervals and, 188191

vs. F distributions, 275, 277, 277t

vs. t distributions, 214215, 215f

in z table, 158166, 159t, B–1

z score(s), 130139

based on mean of sample, 145

calculation of, 131132, 145

central limit theorem and, 145146

comparisons using, 136137, 145146, 160162

definition of, 130

estimation of, 133

formulas for, 132, 134, 145

percentile for, calculation of, 160164

regression with, 396398, 397t, 399401

standard error and, 145

transforming into percentiles, 135, 137138, 148149, 160161, 162

transforming into raw scores, 134136

transforming raw scores into, 130133, 131f, 160161, 162, 177

usefulness of, 137

z statistic and, 140, 145146

z score regression equation, 399401

z statistic, 140, 145146. See also Test statistic

calculation of, 168, 174

vs. t statistic, 218, 220

z table, 158166, 159t, B–1

distribution of means and, 164166

percentages and, 158164

raw scores and, 158164

z test, 170175

one-tailed, 172

SPSS and, 176

steps in, 170175, 177178

two-tailed, 172

vs. t test, 214215

Zacks, J., 336

Zarate, C. A., 124

Zheng, T., 4

Zinman, Jonathan, 326, 331

Zitzewitz, Eric, 326, 331332

Zuckerberg, Mark, 394395, 398