The aim of this book is to present statistical problems and methods in a friendly way to radiologists, emphasizing statistical issues and methods most frequently used in radiological studies (e.g., nonparametric tests, analysis of intra- and interobserver reproducibility, comparison of sensitivity and specificity among different imaging modality, difference between clinical and screening application of diagnostic tests, ect.). The tests will be presented starting from a radiological "problem" and all examples of statistical methods applications will be "radiological".
Author(s): Francesco Sardanelli, Giovanni Leo
Edition: 1
Publisher: Springer
Year: 2008
Language: English
Pages: 252
Cover......Page 1
Foreword......Page 7
Preface to the Italian Edition......Page 9
Preface to the English Edition......Page 14
Acknowledgements......Page 16
2. Variables and Measurement Scales, Normal Distribution, and Confidence Intervals......Page 18
5. Non-Parametric Statistics......Page 19
8. Study Design, Systematic Reviews and Levels of Evidence......Page 20
Subject and Noun Index......Page 21
Evidence-Based Medicine (EBM)......Page 22
Delayed Diffusion of EBM in Radiology and Peculiar Features of Evidence-Based Radiology......Page 26
Health Technology Assessment in Radiology and Hierarchy of Studies on Diagnostic Tests......Page 28
Why do we Need Biostatistics?......Page 32
The Structure of this Book......Page 34
References......Page 36
1. Diagnostic Performance......Page 40
1.1. The Results of an Examination Compared to a Reference Standard......Page 41
1.2. Measures of Diagnostic Performance......Page 42
1.3. Sensitivity, Specificity, FN Rate and FP Rate......Page 43
1.4. Predictive Values, Diagnostic Accuracy and Disease Prevalence......Page 46
1.5. Bayes’ Theorem, Likelihood Ratios and Graphs of Conditional Probability......Page 53
1.6. Cutoff and ROC Curves......Page 57
References......Page 61
2. Variables and Measurement Scales, Normal Distribution, and Confidence Intervals......Page 62
2.1.1. Categorical Variables......Page 63
2.1.3. Continuous Numerical Variables......Page 64
2.1.4. Measurement Scales......Page 65
2.2. Gaussian Distribution......Page 66
2.3.1. Measures of Central Tendency......Page 72
2.3.2 Data Spread about the Measurement of Central Tendency: Variance and Standard Deviation......Page 75
2.4. Standard Error of the Mean......Page 77
2.5. Standard Error of the Difference between Two Sample Means......Page 80
2.6. Confidence Intervals......Page 82
2.7. Confidence Interval of a Proportion......Page 84
References......Page 85
3. Null Hypothesis, Statistical Significance and Power......Page 88
3.1. Null Hypothesis and Principle of Falsification......Page 89
3.2. Cutoff for Significance, Type I or α Error and Type II or β Error......Page 91
3.3. Statistical Power......Page 92
3.4. Why 0.05?......Page 95
3.5. How to Read a p Value......Page 96
References......Page 97
4. Parametric Statistics......Page 98
4.1. The Foundations of Parametric Statistics......Page 99
4.2. Comparison between Two Sample Means: Student’s t Test......Page 101
4.2.1. The Link with Confidence Intervals......Page 106
4.3. Comparing Three or More Sample Means: the Analysis of Variance......Page 107
4.3.1. ANOVA for Independent Groups......Page 108
4.3.2. ANOVA for Paired Data......Page 110
4.4. Parametric Statistics in Radiology......Page 112
References......Page 113
5. Non-Parametric Statistics......Page 114
5.1.1. Variables Measured with Dichotomous Scale......Page 115
5.1.2. Variables Measured with Ordinal Scales......Page 119
5.1.3. Variables Measured with Interval or Rational Scales......Page 121
5.2.1. Variables Measured with Nominal or Ordinal Scales......Page 122
5.2.2. Variables Measured with Interval or Rational Scales......Page 123
5.3.1. Variable Measured with Dichotomous Scale......Page 124
5.4.1. Variables Measured with Nominal or Ordinal Scale......Page 125
5.4.2. Variables Measured with Interval or Rational Scale......Page 126
5.5. Some Considerations Regarding Non-Parametric Tests......Page 127
References......Page 128
6.1. Association and Causation......Page 130
6.2. Correlation between Continuous Variables......Page 132
6.3. Interpreting the Correlation Coefficient......Page 134
6.4. Test for Significance......Page 136
6.5. Rank Correlation......Page 137
6.6. Linear Regression......Page 139
6.6.1. Coefficients for Linear Regression......Page 140
6.7. Interpreting the Regression Line......Page 143
References......Page 145
7.1. Sources of Variability......Page 146
7.2. Why do we Need to Know the Variability of Measurements?......Page 149
7.3. Intraobserver and Interobserver Variability for Continuous Variables: the Bland-Altman Analysis......Page 150
7.4. Interpreting the Results of Bland-Altman Analysis......Page 155
7.5. Intra- and Interobserver Variability for Categorical Variables: the Cohen k......Page 157
References......Page 161
8. Study Design, Systematic Reviews and Levels of Evidence......Page 162
8.1. Phases 1, 2, 3, and 4 of Pharmacologic Research......Page 163
8.2. Study Classification......Page 165
8.3. Experimental Studies and Control Group......Page 166
8.4. Observational Studies......Page 169
8.5. Randomized Controlled Studies: Alternative Approaches......Page 170
8.6. Studies on Diagnostic Performance: Classification......Page 171
8.7. Randomization and Minimization......Page 174
8.8. Sample Size......Page 176
8.9. Systematic Reviews (Meta-analyses)......Page 180
8.10. Levels of Evidence......Page 181
References......Page 184
9. Bias in Studies on Diagnostic Performance......Page 186
9.1. Classification......Page 187
9.2. Bias Affecting External Validity......Page 188
9.2.1. Study Design......Page 189
9.2.2. Subject Selection......Page 191
9.2.3. Radiologic Methods and Reference Standard......Page 194
9.3.1. Protocol Application......Page 196
9.3.3. Data Measurement......Page 197
9.4. A Lot of Work to Be Done......Page 199
References......Page 200
10. How to Write a Radiologic Paper......Page 202
10.1. Major Papers, Minor Papers, Invited Papers......Page 203
10.2. Which Medical Journal?......Page 205
10.3. Do We Always Need Institutional Review Board Approval and Informed Consent?......Page 222
10.4. Title, Running Title and Title Page......Page 223
10.5. Four-section Scheme, Section Size and Editing Sequence......Page 224
10.6. «Introduction»: Why did you do It?......Page 225
10.7. «Materials and Methods»: What did you do and how did you do it?......Page 226
10.8. «Results»: What did you Find?......Page 230
10.9. «Discussion»: What is the Meaning of your Findings?......Page 231
10.10. «References»......Page 232
10.11. «Abstract» and «Keywords»......Page 233
10.13. Other Recommendations......Page 234
10.14. Dealing with the Editor’s Response and the Reviewers’ Opinions......Page 236
10.15. To Conclude......Page 239
References......Page 240
B......Page 242
C......Page 243
D......Page 244
F......Page 245
I......Page 246
M......Page 247
P......Page 248
R......Page 249
S......Page 250
V......Page 251
Y......Page 252
