Medical Statistics at a Glance

Aviva Petrie is Honorary Associate Professor, Biostatistics Unit, UCL Eastman Dental Institute, London, UK.

Caroline Sabin is Professor of Medical Statistics and Epidemiology, Department of Primary Care and Population Sciences, Royal Free and University College Medical School, London, UK.

Preface ... IX

Part 1 Handling data ... 1
1 Types of data ... 2
2 Data entry ... 4
3 Error checking and outliers ... 6
4 Displaying data diagrammatically ... 8
5 Describing data: the ‘average’ ... 10
6 Describing data: the ‘spread’ ... 12
7 Theoretical distributions: the Normal distribution ... 14
8 Theoretical distributions: other distributions ... 16
9 Transformations ... 18

Part 2 Sampling and estimation ... 21
10 Sampling and sampling distributions ... 22
11 Confidence intervals ... 24

Part 3 Study design ... 27
12 Study design I ... 28
13 Study design II ... 31
14 Clinical trials ... 34
15 Cohort studies ... 37
16 Case–control studies ... 40

Part 4 Hypothesis testing ... 43
17 Hypothesis testing ... 44
18 Errors in hypothesis testing ... 47

Part 5 Basic techniques for analysing data ... 51
Numerical data
19 Numerical data: a single group ... 52
20 Numerical data: two related groups ... 54
21 Numerical data: two unrelated groups ... 57
22 Numerical data: more than two groups ... 60
Categorical data
23 Categorical data: a single proportion ... 63
24 Categorical data: two proportions ... 66
25 Categorical data: more than two categories ... 69
Regression and correlation
26 Correlation ... 72
27 The theory of linear regression ... 75
28 Performing a linear regression analysis ... 77
29 Multiple linear regression ... 81
30 Binary outcomes and logistic regression ... 85
31 Rates and Poisson regression ... 89
32 Generalized linear models ... 93
33 Explanatory variables in statistical models ... 96
Important considerations
34 Bias and confounding ... 100
35 Checking assumptions ... 104
36 Sample size calculations ... 107
37 Presenting results ... 111

Part 6 Additional chapters ... 115
38 Diagnostic tools ... 116
39 Assessing agreement ... 119
40 Evidence-based medicine ... 124
41 Methods for clustered data ... 127
42 Regression methods for clustered data ... 130
43 Systematic reviews and meta-analysis ... 134
44 Survival analysis ... 138
45 Bayesian methods ... 142
46 Developing prognostic scores ... 144

Appendices ... 147
A Statistical tables ... 148
B Altman’s nomogram for sample size calculations (Chapter 36) ... 155
C Typical computer output ... 156
D Checklists and trial profile from the EQUATOR network and critical appraisal templates ... 169
E Glossary of terms ... 178
F Chapter numbers with relevant multiple-choice questions and structured questions from Medical Statistics at a Glance Workbook ... 188

Index ... 190