Approximation of the Distribution of the Location Parameter in the Growth Curve Model

Abstract.  In this paper an Edgeworth-type approximation of order O(n ⁻² ) to the density of the estimator of the location parameter in the growth curve model has been derived. The approximation is a mixture of a normal and a Kotz-type distribution, thus being an elliptical distribution. A condition for unimodality of the mixture was found and marginal distribution of a subvector of the mixture distribution was derived. Finally, a small example was given to demonstrate an application of the approximation.     

Incentives for Increasing Return Rates: Magnitude Levels, Response Bias, amd Format

The use of monetary incentives has been shown to significantlyincrease response rate. However, previous investigations haverarely investigated the effects of incentives greater than $1,compared different magnitudes of incentives, or investigatedresponse bias due to incentives. The current study also investigatedthe utility of an Answer Check. Results suggest that monetaryincentives increase response rate, larger incentives do notnecessarily further increase survey response, incentives donot appear to bias responses, and the Answer Check does notfacilitate response rate.