Pediatric Pathology, Abstract 271–280, Study Group

Abstract

This paper outlines the common statistical methods used to analyze four types of observational study: ecological studies, cross-sectional studies, case–control studies and cohort studies. Three statistical methods are considered in detail: correlation coefficients, t-tests for the difference between two means from independent samples and odds ratios. For each method, the need for the same four key outputs is highlighted: the measure of effect, its precision (95% confidence interval), its statistical significance (p-value) and its clinical significance (comparison to the minimum important difference). Where possible, this paper explains the derivation of measures of effect and statistical significance to help readers understand where the numbers come from. The paper also highlights other important aspects of analyzing the quantitative data collected in an observational study, potential biases to consider, and good practice in reporting. Examples from relevant pediatric studies are used where appropriate.