A primer on validity and design terminology in comparative designs

An overview of terminology (independent and dependent designs, dependent and independent variables) and validity (internal, external, and measurement) is given using six different scenarios. For simplicity of exposition, all examples have factors at two levels

An example motivated discourse of the chi-squared test of association (2 by 2)

An example application of the chi-square test of association is given through a set of questions and answers. The emphasis is on methodological aspects and what can be legitimately inferred, if anything. It is strongly highlighted that statistical conclusions can be drawn from a study, but these statistical conclusions might not translate into research or scientific conclusions

That assumption of normality

Many statistical tests are based around an assumption of “normality”. The reasoning for this choice of distribution, whether to test, what to test, and how to test for normality is covered along with practical recommendations

An example motivated discourse of the paired samples t-test

An application of the paired samples t-test is used to discuss the logic underpinning the test and to consider what may be legitimately inferred

Cohen’s d for two independent samples

An exposition of standardized effect for two independent samples (under an assumption of normality) is given along with an insight into interpretation and reportin

A primer on statistical hypotheses and statistical errors

An abstract overview of some of the logic and statistical considerations in quantitative inference is give

An example motivated discourse of the independent samples t-test and the Welch test

Analyses are given for two example scenarios. Both scenarios comprise two independent samples. One scenario is analysed using the independent samples t-test; the other the Welch test. Commentary on the designs and limitations is given through a question and answer process

Challenge and change: Police identity, morale and goodwill in an age of austerity

One of the largest pieces of independent research on police attitudes in England and Wales. The research, led by Dr James Hoggett from UWE Bristol (the University of the West of England, Bristol), looked at police attitudes to current reform proposals that may impact on the profession. 13,591 police officers across 43 forces in England and Wales responded to a questionnaire into attitudes and morale amongst officers. The response rate reflects the views of about 10% of all serving police officers in England and Wales. The attitude and morale data provided consistent messages across the sample with only minor variations between ranks of officer or between police forces

A reverse look at p-values

An overview of p-values is given. The usual way of being introduced to p-values is by considering the rigorous development of statistical tests, then their use for decision making. This note takes a reverse view by firstly considering their use in decision making, then their distributions, before looking at the statistical test