Handling data: what steps are important

Data entry 102 Forms which can be automatically scanned for data entry 106 Variable names and labels 108 Joining datasets 110 Joining datasets: examples 112 Storing and transporting data 114 Data checking and errors 116 Data checking: examples 118 Formal data monitoring 122 Statistical issues in data monitoring ...

Glossary of terms

Analysis of variance See One-way analysis of variance (p. 280) and Two-way analysis of variance (p. 412) Bayes’s theorem A formula that allows the reversal of conditional probabilities (see Bayes’ theorem, p. 234) Bayesian statistics A statistical approach based on Bayes’ theorem, where prior information or beliefs are combined with new data to provide estimates of unknown parameters (see ...

Diagnostic studies

Sensitivity and specificity 340 Calculations for sensitivity and specificity 342 Effect of prevalence 344 Likelihood ratio, pre-test odds, post-test odds 346 Receiver operating characteristic (ROC) curves 348 Links to other statistics 350 In this chapter we describe how statistical methods are used in diagnostic testing to obtain different measures of a test’s performance. We describe how to calculate sensitivity, specificity, and positive and negative predictive values, and show the relevance of pre- and post-test odds and likelihood ratio in evaluating a test in a clinical situation. We also describe the receiver operating characteristic curve and show how this links with logistic regression analysis. All methods are illustrated with examples....

Presenting research findings

Communicating statistics 128 Producing journal articles 130 Research articles: abstracts 132 Research articles: introduction and methods sections 134 Research articles: results section 136 Research articles: discussion section 138 Presenting statistics: managing computer output 140 Presenting statistics: numerical results 142 Presenting statistics: P values and confidence intervals ...

Summarizing data

Why summarize data? 174 Types of data 176 Quantitative data 178 Categorical data 180 Summarizing quantitative data 182 Calculation of mean, SD 184 Calculation of median, interquartile range 186 Geometric mean, harmonic mean, mode 188 Choosing a summary measure for quantitative data 190 Summarizing categorical data ...