380 Biostatistics For Dummies

root-mean-square (RMS), 222

roots, 21

Rothman’s causal pie, 297–298

round-off error, 352

RR (rate ratio), 195–196

RStudio, 58

Rumsey, Deborah J. (author)

Statistics For Dummies, 2, 29

Statistics II for Dummies, 29

S

safety considerations, 70

safety objectives, 62–63

safety study, 62

sample size

for chi-square and Fisher exact tests, 171–172

for cohort studies, 95–96

compared to power and effect size, 44–47

for comparing averages, 158

for correlation tests, 206–207

estimating, 198, 361–367

introduction to, 14

for logistic regression, 268–269

for multiple regression, 247–248

relation to confidence intervals, 130–131

for straight-line regression, 230–231

for survival comparisons, 324–325

for survival regression, 346–347

sample statistic, 175

samples. See also sample size

framing, 78–79

introduction to, 9–10, 14

selecting, 33–37, 68, 78–80

types of, 80–86

sampling clusters, 83–84

sampling distribution, 38

sampling error, 34, 78

sampling frame, 78

sampling strategies, 175–176

SAP (Statistical Analysis Plan), 70

SAS (Statistical Analysis System), 54–56, 58, 110

SAS OnDemand for Academics (ODA), 55–56

SBP (systolic blood pressure)

comparing, 39

effect of drugs on, 62, 123–125

relation between weight and, 218–229

variable name of, 18

scatter plots

creating, 219, 238–240

example of, 221

types of, 214

Scheffe’s test, 154–156

scientific notation, 28

screening tests, 184–187

SD (standard deviation), 119, 123, 143, 222

SE (standard error)

calculating, 147–148, 179–180

of coefficients, 225–226, 340

compared to confidence intervals, 130–131

description of, 38, 129, 163, 242

in a fraction, 41

secondary efficacy objective, 62

secondary objectives, 62

sensitivity, 185–186, 262–264

sigma (Σ), 27–28

significance, 40, 42–43, 174

significance tests. See statistical tests; specific test

names

significant association, 11

significant correlation, 363–364

simple formulas, 24

simple random samples (SRS), 80–81

simple randomization, 66

simple regression, 209

simulation, 79

single-blinding, 66

single-precision numbers, 107

single-site study, 104

skewed data, 11, 114, 121, 353

skewness, 121

skewness coefficient (γ), 121

slope row, 224

slopes, 215–217, 221, 224–231