what is correlation testing why is correlation testing useful in statistical tests why does pearson's r test for correlation why use pearson's statistic why is correlation important why use correlation method why use correlation in quantitative research why use pearson's correlation method why is correlation used in a statistical testing method why use pearson's correlation method why use pearson's r in correlation research? why do we use pearson's method of correlation in research why correlation in statistics why do you use pearson's r method can pearson's r be an end in itself why pearson's r is used why correlation test does pearson's correlation work? why is correlation used in research why is correlation used