Weighing the evidence
This chapter describes how to look at statistics from published studies and check existing statistics in existing studies. It discusses how to use Excel to evaluate the validity and significance of existing studies. The chapter tells how to use statistics in our own studies plot scatter graphs to look at comparisons of continuous data to carry out correlation and regression analysis in Excel carry out t-tests in Excel and calculate confidence intervals and sample sizes. Correlation analysis is used to analyse the association between two or more variables. The chapter considers Excel's use in a study by Mazess et al. The study investigated the association between a patient's age and the percentage of their body weight stored as fat. The chapter uses an example from the British Medical Journal to illustrate how a paired t-test can be used to evaluate an intervention.