How to evaluate and quantify the influence of coincidence on fertility and herd health parameters?: a practical overview of frequently used and abused statistical techniques in research and practice

In this article, frequently encountered statistical questions and methods used both in research and in daily practice are described and explained. First, the concepts of variability and uncertainty are explained and illustrated. From this, it is explained how variation can be quantified and how the limits of what can be expected as a result of normal variation are determined both for continuous and binary data. Based on the basic concepts of probability theory, an introduction to risk assessment was given. Finally it is explained how to test whether individual observations lie outside the normal range or the test whether populations are different from each other. All these are carried out avoiding theory and formulas as much as possible and illustrated with real examples from reproduction and herd health