The Choice Between Fixed and Random Effects Models: Some Considerations for Educational Research We discuss fixed and random effects models in the context of educational research and set out the assumptions behind the two approaches. To illustrate the issues, we analyse the determinants of pupil achievement in primary school, using data from the Avon Longitudinal Study of Parents and Children. ...

In studies of subjective well-being, economists and other researchers typically use a fixed or random effect estimation to control for unobservable heterogeneity across individuals. Such individual heterogeneity, although substantially reducing the estimated effect of many characteristics, is little understood. This paper shows that personality measures can account for 20% of this heterogeneity...

We discuss the use of fixed and random effects models in the context of educational research and set out the assumptions behind the two modelling approaches. To illustrate the issues that should be considered when choosing between these approaches, we analyse the determinants of pupil achievement in primary school, using data from the Avon Longitudinal Study of Parents and Children. We conclude...

An alternative to the classical mixedmodel with normal random effects is to use a Dirichlet process to model the random effects. Such models have proven useful in practice, and we have observed a noticeable variance reduction, in the estimation of the fixed effects, when the Dirichlet process is used instead of the normal. In this paper we formalize this notion, and give a theoretical justifica...

In this paper I discuss economic processes that may give rise to spatial patterns in data, and explore the relative merits of alternative modeling approaches when data are spatially correlated. Specifically, I present an estimation scheme that allows for spatial random effects, and focus attention on cases in which such a framework may be preferred to the more general fixed effects framework th...

Background: Several studies have shown that administration of magnesium sulfate prolongs the bleeding time. Objective: To investigate such effects in pregnant women in Shiraz, southern Iran.  Methods:This study was conducted on 30 pregnant women aged between 18 and 32 yrs, with a gestational age of 20 to 37 weeks, who presented to Hafez and Zeynabiyeh Emergency Units affiliated to Shiraz Univer...

This study presents the effects of project uncertainties on nonlinear time-cost tradeoff (TCT) profile of real life engineering projects by the fusion of fuzzy logic and artificial neural network (ANN) models with hybrid meta-heuristic (HMH) technique, abridged as Fuzzy-ANN-HMH. Nonlinear time-cost relationship of project activities is dealt with ANN models. ANN models are then integrated with ...

biophysical profile (bpp) test is the most commonly used antenatal test of fetal well-being. purpose of this study is determining the influence of acoustic stimulation (as) on bpp testing time. about 55 pregnant women at 35 to 42 weeks who referred to department of obstetric & gynecology at university of medical sciences, tabriz, iran, were selected randomly. we used abdominal ultrasound guidan...