From Section 6.1.5 and Exercise6.31,thecorrelationisa standardizedslope. Whenwefita multipleregressionmodeltostandardizedversionsof y and theexplanatoryvariables,the estimated regressionparametersarecalled standardizedregressioncoefficients.

(a) Explainhowtointerpretthestandardizedcoefficientfor xj .

(b) Tocompareeffectsofvariableswithverydifferentunits(e.g.,cholesterollevel,systolic bloodpressure,weight,age,andnumberofyearsofeducation),explainwhyitismore meaningful tocomparethestandardizedthantheordinaryregressioncoefficients.