SummaryCorrelation analysis in applied psychologySome of the problems treated by correlation methods are, in applied psychology (test psychology):investigation of test reliabilityitem‐validationvalidation of tests and testing programsrelationships between testsfactor analysis.As an example the author discusses the validation of a selection test used in Dutch technical schools.Statistical psychology in the Netherlands is still in its infancy, but the greatest obstacle to its growing up has been removed, viz. the opinion that quantitative methods are not, as a matter of principle, applicable to problems in psycholog