Jens Petter Gitlesen

Empirical Evaluation of Alternative Model Specifications to Predict Commuting Flows

This study is devoted to empirical and modeling aspects on how characteristics of spatial structure influence commuting flows. Within a doubly-constrained framework, results from a competing-destinations formulation are evaluated and compared to results from the traditional gravity model. The evaluation depends critically upon the specification of within-zone journeys-to-work. Specific labor-market characteristics are found to be significant to explain how workers are absorbed in diagonal elements of the trip-distribution matrix. We also find that the parametric specification of the accessibility measure is important, and that the competing-destinations formulation is superior to the traditional gravity model.

The overlap between psychiatric symptoms and challenging behaviour: a preliminary study.

Increasingly, challenging behaviour is explained by way of psychiatric symptomatology. This poses possible pitfalls. First, the possibility exists that both psychiatric symptoms and challenging behaviour are concurrent expressions of common underlying factors. Second, psychiatric symptoms may be rated as present on the basis of challenging behaviour, which may render it more difficult to explain the latter by way of the former. The present study was conducted in order to investigate possible overlaps between psychiatric symptoms and challenging behaviour, when symptoms are rated by caregivers. The results indicate considerable overlaps. Implications for explaining challenging behaviour are discussed, as well as limitations of the study, first and foremost the use of untrained assessors and small sample size.

An Empirically Based Implementation and Evaluation of a Network Model for Commuting Flows

In this paper we present empirical results based on a network model for commuting flows. The model is a modified version of a construction introduced in Thorsen et al. (1999). Journeys-to-work are determined by distance deterrence effects, the effects of intervening opportunities, and the location of potential destinations relative to alternatives at subsequent steps in the transportation network. Calibration is based on commuting data from a region in Western Norway. Estimated parameter values are reasonable, and the explanatory power is found to be very satisfying compared to results from a competing destinations approach. We also provide theoretical arguments in favor of a network approach to represent spatial structure characteristics.

Laboratory Testing of Spurious Spatial Structure in Trip Distribution Models

Abstract In this paper we examine the risk of reporting spurious relationships in trip distribution models. We show how to make synthetic data sets that (by construction) are neutral with respect to clustering effects. We study a particular case with two non-interacting groups of jobs/workers. A competing destinations model is applied to 100 randomly drawn data sets of this type. Quite disturbingly, the loglikelihood ratio test reported a significant clustering effect in all of these data sets. This shows that statistical tests based on likelihood values may not be the right tool to examine the effect of such model extensions.