The rise of quantitative methods in psychology

Quantitative methods have a long history in some scientific fields. Indeed, no one today would consider a qualitative data set in physics or a qualitative theory in chemistry. Quantitative methods are so central in these fields that they are often labelled “hard sciences”. Here, we examine the question whether psychology is ready to enter the “hard science club” like biology did in the forties. The facts that a) over half of the statistical techniques used in psychology are less than 40 years old and that b) the number of simulations in empirical papers has followed an exponential growth since the eighties, both suggests that the answer is yes. The purpose of Tutorials in Quantitative Methods for Psychology is to provide a concise and easy access to the currents methods. The use of agreed‐upon quantitative methods is maybe the most reliable defining feature of the so‐called ʺ hard sciencesʺ. This trend was initiated by Descartes in the study of optics and, with a greater impact, by Galileo in the study of motion over four centuries ago. By 1905, the mutation they initiated fully matured, yielding among other, Einsteinʹs relativity theory and Planckʹs quantum theory of the black box radiation. The quantum mechanic that evolved in the subsequent ten years was so mathematically involved (using the by‐then weird matrix multiplication) that no vulgarization book appeared until the late 1940 (Hoffmann, 1947). Browsing the 1905 volume of the Physical Review, it is clear that qualitative measures and qualitative theories have completely disappeared from this field of research.