Index 379

R

R (software)

description of, 58

nonlinear regression, 282–286

odds ratio calculation, 183

risk ratio calculation, 180–181

straight-line regression, 221

r value, 203–206

radiation exposure, 251–256, 260–263, 267,

337–338

radical sign (√), 21

random number generator (RNG), 80–81

random shuffling, 67

random variability, 158

randomization, 97, 171

randomized controlled trials (RCTs), 65–67, 98

randomness, 33

range, 120

ranks, 49

rate ratio (RR), 195–196

ratio data, 102, 107–108

rationale, 69

RCTs (randomized controlled trials), 65–67, 98

Receiver Operator Characteristics (ROC), 257,

264–265

reference level, 237

regression

logistic

basics of, 251–254

definition of, 12, 210

disadvantages of, 266–268

evaluating, 257–265

sample size for, 268–269

using, 249–250, 255–257

multiple

basics of, 234–235

introduction to, 26

sample size for, 247–248

special considerations, 245–247

using, 236–245

multivariable, 291

ordinary, 210

straight-line

basics of, 215–216

disadvantages of, 229–231

evaluating, 220–224

using, 216–220

when to use, 213–215

survival

concepts of, 329–335

definition of, 210

evaluating, 337–343

sample size for, 346–347

using, 335–336

when to use, 328–329, 343

univariate, 209

regression analysis, 12, 207–208

regression models, 68, 208–209

relative frequency, 30

relative risk, 95, 178–181

REM (Roentgen Equivalent Man), 251–254,

260–262, 267

research

analytic, descriptive and observational, 88–90

animal, 1

epidemiological, 1, 9–12

experimental, 61, 88–90, 97–98

human health, 88

longitudinal, 90

research studies, 1

residual information, 242

residual standard error, 222, 242

residuals, 222–224, 242–245

residuals versus fitted graph, 222–223

retinopathy, 292–293

right skewed data, 121

risk ratio, 96, 178–181

RMS (root-mean-square), 222

RNG (random number generator), 80–81

ROC (Receiver Operator Characteristics), 257,

264–265

Roentgen Equivalent Man (REM), 251–254,

260–262, 267

Roman letters, 17