Calculating and reporting effect sizes on scientific papers (2): Guide to report the strength of relationships

In the first issue of the Portuguese Journal of Behavioral and Social Research, it was described the importance of calculating, indicating and interpreting the effect sizes for the differences between means of two groups. The PJBSR intends to continue to remind of the importance of reporting effect sizes for other statistical tests. The magnitude of the strength of the relationships was not indicated in the previous paper, and it may not be known that correlation is an effect size. Thus, this paper intends to provide some guidelines to the authors on the procedures for calculating the Pearson correlation coefficient and some correlation coefficients for special data (Spearman Rho, Kendall’s Tau, Point-biserial and biserial, Phi, Cramér’s V, and Eta). For this purpose, the formulas, steps in the SPSS (Statistical Package for the Social Sciences), assumptions and precautions, classification of values and their interpretation will be presented. Since SPSS does not compute all the mentioned coefficients, five spreadsheets (3 ways of comparing correlations, point-biserial and biserial, and correction of correlations for samples < 60) were included in the article supplements.