Variance of means versus mean of variances: A contrarian view on operationalizing group dispersion Conference

Sin, HP, Newman, DA. (2005). Variance of means versus mean of variances: A contrarian view on operationalizing group dispersion .

cited authors

  • Sin, HP; Newman, DA

authors

abstract

  • Common practice in calculating within-group dispersion (VARwg and SDwg) and within-group agreement (rwg) includes first estimating within-group variance at the item level, then averaging across item-level variances. Using classical test theory, we illustrate problems with the common approach. Estimating dispersion and agreement via scale scores is recommended, and implications of item-specific and raterspecific variance for indexing substantive dispersion constructs are discussed.

publication date

  • December 1, 2005