The dramatic loss of statistical power when dichotomising continuous variables
*Correspondencia: Dra. Carmen Carazo-Díaz. Universidad Católica San Antonio de Murcia. Avenida de los Jerónimos, 135. E-30107 Guadalupe de Maciascoque, Murcia.
E-mail: ccarazo@ucam.edu
Abstract. A very common practice in medical research, during the process of data analysis, is to dichotomise numerical variables in two groups. This leads to the loss of very useful information that can undermine the effectiveness of the research. Several examples are used to show how the dichotomisation of numerical variables can lead to a loss of statistical power in studies. This can be a critical aspect in assessing, for example, whether a therapeutic procedure is more effective or whether a certain factor is a risk factor. Dichotomising continuous variables is therefore not recommended unless there is a very specific reason to do so.
