A Short Guide to Statistical Tests. This booklet contains all the information students need for the inferential statistics section of OCR A Level Psychology. It includes: How to know which test to use Levels of measurement (nominal/ordinal/interval) Significance levels How to tell if your result is significant (+ a nice easy rule for remembering!) Binomial sign test instructions Chi-square instructions Wilcoxon T instructions Mann-Whitney U instructions Spearman’s rho instructions How to interpret correlations & correlation coefficients