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Figure 1: Scatter plots of relationship between values of two quantitative variables and their corresponding correlation coefficient (r) values. "r " can vary between − 1.0 and + 1.0. If as the values of one variable (say on Xaxis) increase, those of the other variable (on Yaxis) increase, "r " is positive (ac); however, if the latter decrease, "r " is negative (df). When the values of two variables have no clear relation, "r " is zero (g). The absolute values of "r " are higher when the individual data points are closer to a line showing the linear trend (a > b > c; d > e > f) r " can vary between − 1.0 and + 1.0. If as the values of one variable (say on Xaxis) increase, those of the other variable (on Yaxis) increase, "r " is positive (ac); however, if the latter decrease, "r " is negative (df). When the values of two variables have no clear relation, "r " is zero (g). The absolute values of "r " are higher when the individual data points are closer to a line showing the linear trend (a > b > c; d > e > f)"> 
