Page 383 - Statistics for Dummies

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self-selected, 49
size of, 255–256
of bias, 323–324
target population, representing, 254
checking, 39
media, 33
volunteer, 49
sampling distribution
original, 33
for surveys, 246–247
if X does not have normal distribution,

170–173
specific values of X, fi nding probabilities
if X has normal distribution, 170
for, 140–141
sports section of newspaper, statistics in,
mean, 164–166
overview, 163–164
27–28
of sample proportion, 175–177
spread of data in histograms, 106
shape of, 170–173
standard deviation
sampling error, 58, 324
binomials, 142
calculating, 77–78
scale
bar graphs, 100–101
described, 52–53, 110
described, 37–39
importance of, 79–80
histograms, 114
interpreting, 78–79
normal distribution, 143
time charts, 125–126 sources Index 367
scatterplot properties of, 79
creating, 281 standard error
interpreting, 281–282 measuring variability with, 218–219
overview, 280 overview, 166, 183–184

school proficiency, statistics about, 26–27 population standard deviation, 167–169

scientific method, 43–45 sample size and, 166–167
self-selected sample, 49 standard normal distribution
sense, analyzing your exam answers to formula for, 147
confirm they make, 344–345 overview, 54–55, 56, 146–147

setting up relationship to t-distribution, 231
cells in two-way tables, 297 standardizing, 147–148
histograms, 105–106 tables, 347–349
hypothesis test, 216–217 t-distribution compared, 157–158

sexual activity, statistics about, 29 Z-table used to find probabilities for Z,
shape of data in histograms, 106–109 148–149
shape of sampling distribution, 170–173 standard scores

significance level, 223 hypothesis test, 219
68-95-99.7% rule, 53, 81–83, 112 overview, 54
size of sample, 255–256 standard treatment in experiments, 266
skepticism about statistics, 22, 33 standardizing, 54
skewed left start/end points, 125
boxplots, 117 state lottery profits, bar graphs for, 99–100

described, 75 statistical analyses, 274–275
histograms, 107, 111–112 statistical signifi cance, 61–62
skewed right statisticians
boxplots, 117–118 described, 43
described, 75 in workplace, 32
histograms, 107, 111–112 statistics. See also confi dence intervals
slope of regression line, 289–291 in daily life, 9–10
described, 50, 194
linked to parameters, 194–195
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