378 Biostatistics For Dummies

participants. See also sample size; samples

enrolling, 68

protection for, 71–73

selecting, 64–65, 236–237

PatSat, 106

PCR (polymerase chain reaction), 184

Pearson, Karl (biostatistician), 161

Pearson Correlation test, 47–49, 227

Pearson kurtosis index, 122

percentile, 120

perfect predictor problem, 267–268

perfect separation, 267–268

periodicity, 83

PH (proportional hazards regression), 330–331,

333–334

pharmacokinetic (PK) properties, 280–282

pi (Π), 27–28

pie charts, 113

pilot study, 230

placebo, 66–67, 171, 187–188

placebo effect, 66, 187–188

plain text format, 16, 24

platykurtic distribution, 122

Plummer, Walton D. (biostatistician), 60

pointy-topped distribution, 114

poisson distribution, 36, 355

poisson regression

definition of, 12, 210

using, 271–278

polymerase chain reaction (PCR), 184

populations, 33–37, 175

positive predictive value (PPV), 187

positively skewed data, 121

post-hoc tests, 143, 152–157

potential confounding variables, 64

Power and Sample Size Calculation (PS)

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

definition of, 60

for survival comparisons, 324–325

power calculations, 47, 171–172, 361, 365

powers, 20–21, 41, 44, 45–47, 206

PPV (positive predictive value), 187

precision, 37, 38, 147

predicted values, 242

predictive model, 228–229

predictive value negative, 187

predictive value positive, 187

predictors

introduction to, 208, 233

in iterative models, 246–247

in logistic models, 255–256

in regression models, 273–274, 279

relation to the outcome, 242, 245–246, 250

types of, 209, 235–236

pregnancy, 171, 185–187

prevalence, 179, 186, 191–194

prevalence ratio, 179

primary diagnosis (PrimaryDx), 236–238

primary efficacy objective, 62

primary objectives, 62

primary sampling units (PSU), 86

privacy, 71

probability, 30–33

probability bell curve, 353

probability distributions, 35–37

probability of independence, 166

procedural descriptions, 70

product, of an array, 27

prognosis curves, 329, 331, 343–346

proportional hazards (PH) regression, 330–331,

333–334

proportions, 11, 135–136, 363

protective factor, 178

protractor, 113

PS (Power and Sample Size Calculation)

for chi-square and Fisher exact tests,

171–172

definition of, 60

for survival comparisons, 324–325

pseudo-r-squared values, 259

PSU (primary sampling units), 86

Python, 58