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A scatter diagram is used to show the relationship between two quantitative variables.This implies that all values for the independent variable are graphed with the X values and dependent variables graphed with the Y values.Then you compute a correlation co-efficient between the two data sets.Statistical correlation is measured by what is the coefficient of correlation (r). If the numerical value ranges from +1.0 to -1.0., it gives an indication of the strength of relationship.
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