372 Biostatistics For Dummies

D

data. See also cross-tabulated data

analyzing and collecting, 1, 7, 9–10, 74–76,

101–110

categorical, 112–114

free-text, 103

interval and ordinal, 102

ratio, 102, 107–108

skewed and unskewed, 11, 114, 121, 353

survival, 208, 301–306, 337, 343

time, 108–110

data close-out, 76

data dictionary, 110

data safety monitoring board (DSMB), 73, 76

data safety monitoring committee (DSMC), 73

data snapshot, 76

date data, 108–110

date of last contact, 303

DBP (diastolic blood pressure), 116–117

deciliter (dL), 280

decision theory, 10, 39–40

degrees of freedom (df)

calculating, 147–148, 152–153

for chi-square tests, 166–167, 358–359

dementia, 91, 146, 187–188

denominator, 41–42

dependent variable, 208, 213, 235–245

descriptive research, 88–90

descriptive study designs, 91

desired power, 347

desired α level, 347

determinants, 191

deviation, 119, 258–259

df (degrees of freedom)

calculating, 147–148

for chi-square test, 166–167, 358–359

numerator and denominator, 152

diabetes, 135–136, 236–240.See also Type II

diabetes

diagnostic procedures, 183–188

diastolic blood pressure (DBP), 116–117, 123–124

dichotomous variables, 173–174, 249, 269

difference, 147–148, 163

difference table, 163

disease, 191, 193–194

dispersion, 115, 119

distribution center, 115

distributions

bimodal (two-peaked), 114–117

binomial, 36, 354–355

chi-square, 165–166, 358–359

exponential, 356

Fisher F, 152, 359–360

frequency, 47–48

leptokurtic and platykurtic, 122

normal, 13, 36, 114, 353

probability, 35–37

sampling, 38

statistical, 13

student t, 357–358

weibull, 330, 356–357

District of Columbia, 34–35

division, 20

dL (deciliter), 280

dose-response relationship, 298

double-blinding, 66, 97

double-precision numbers, 107

drug description, 70

drug development research, 280–282

DSMB (data safety monitoring board), 73, 76

DSMC (data safety monitoring committee), 73

Dupont, William D. (biostatistician), 60

E

ECG (electrocardiogram), 188

ecologic fallacy, 93

ecologic studies, 91–93

effect modification, 296–297

effect size

compared to power and sample size, 45–47

definitions of, 362–364

example of, 39

of importance, 158, 206, 361