Correlation research is a quantitative research method in which 2 or more variables from the same group of subjects are studied and any correlation between them is determined. In general, when we study any seemingly related (or even unrelated) properties or aspects of a population group, we can see that they may be positively or negatively correlated.

An example is a study of high school students and the variables of interest are school scores and number of hours spent on gaming. Given quantitative data on each of these variables for a large enough population (at least more than 30 subjects), we can calculate if these variables are correlated or not. In other words, we can see from this correlation research study if there is a positive or negative effect of spending time on gaming on school scores.

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