An approach to sample size planning for multiple regression is presented that
emphasizes accuracy in parameter estimation (AIPE). The AIPE approach yields
precise estimates of population parameters by providing necessary sample sizes in
order for the likely widths of confidence intervals to be sufficiently narrow. One
AIPE method yields a sample size such that the expected width of the confidence
interval around the standardized population regression coefficient is equal to the
width specified. An enhanced formulation ensures, with some stipulated probability,
that the width of the confidence interval will be no larger than the width
specified. Issues involving standardized regression coefficients and random predictors
are discussed, as are the philosophical differences between AIPE and the
power analytic approaches to sample size planning.