Page 375 - Statistics for Dummies

359
conclusions
avoiding jumping to, 316
countably infinite values, 46, 133

counts, 103
cause and effect, questioning claims of,
cover letter for surveys, 253
21–22
drawing, 259–260
crime rates, 35–36
overstated results in, 21
crime statistics, 35–36
critical value, 198
overview, 21
customer satisfaction statistics, 31–32
conditional distributions
calculating, 305–306
cutoff points, 223
graphing, 306–308
cynical attitude about statistics, 22
overview, 305
• D •
confi dence intervals

choosing confidence level for, 198–199
evaluating, 213
daily life statistics, 9–10
interpreting, 196–197
data
misleading, 213
bias in, 274
overview, 59–60, 195–196
categorical, 46
for population mean, 201–204, 208–211 correlation coeffi cient, 283 Index 359
continuous, 46
population proportion, 206–207, 211–213 discrete, 46
population variability, 201 numerical, 46
sample size, 199–200, 204–206 ordinal, 47
t-table, 161–162 overview, 45–47
width of, 197–198 qualitative, 46
confi dence levels quantitative, 46
choosing, 198–199 reliability of, 273
described, 195 validity of, 273
margin of error (MOE), 184, 188–189 yes/no, 46
z-value for, 198–199 data collection
confidential respondents, 257 experiments, 273–274

confounding variables hypothesis test, 217–218
described, 294 overview, 12
experiments, 270–271 random sample selection, 13
mistake recognition, 327–328 sample selection, 13
consumers of information, 33 data fishing, avoiding, 329–330

continuous data, 46 data set, 47
continuous random variables, 132–133, 143. decisions based on results of experiments,
See also normal distribution making informed, 277–278
control group, 57, 266 degrees of freedom (df), 158, 160
correlation dependent variables, 287, 308, 311–312
calculating, 283–284 descriptive statistics
cause and effect relationship compared, categorical data, 68–71
293–294 empirical rule, 81–83
described, 20, 63, 282 five-number summary, 89–90

detecting misinterpreted, 326–327 histograms, 74–76
interpreting, 284–286 interquartile range, 90
properties, 286 mean, 71–73
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