where ˆ
j is the observed standardized regression coefficient, j represents a specific predictor (j 1, . . . , p), p is the number of predictors (independent or concomitant variables, covariates, or regressors), R2 is the observed multiple correlation coefficient of the model, R2XXj represents the observed multiple correlation coefficient predicting the jth predictor (Xj) from the remaining p − 1 predictors, and N is the sample size (Cohen & Cohen, 1983; Harris, 1985).6 The value that is added to and subtracted from ˆ j to define the upper and lower bounds of a symmetric confidence interval is defined as w, which is the halfwidth of the entire confidence interval. Thus, the total width of a confidence interval is 2w. The value of w is of great importance for accuracy in estimation, because the width of the interval determines the precision of the estimated parameter.