Correlation Coefficient for Continuous and Discrete Data

The purpose of this paper is to introduce researchers to correlation coefficient calculation. The Pearson Product Moment Correlation Coefficient is the most common type of correlation; however, the Pearson correlation coefficient may not be applicable in all cases. The Pearson r is used only when the data of the dependent and independent variables are quantitative. There are many types of correlation coefficient. The correct choice of correlation coefficient depends on the classification of the independent variable (X) and dependent variable (Y). Data are classified into one of three types: quantitative, nominal and ordinal. This writing explains various types of correlations on the basis of X-by-Y data type combination. Using the wrong type of correlation coefficient would lead to faulty inference; as the result, the researcher would commit Type 2 error.