Methodological and empirical challenges in modelling residential location choices

The modelling of residential locations is a key element in land use and transport planning. There are significant empirical and methodological challenges inherent in such modelling, however, despite recent advances both in the availability of spatial datasets and in computational and choice modelling techniques. One of the most important of these challenges concerns spatial aggregation. The housing market is characterised by the fact that it offers spatially and functionally heterogeneous products; as a result, if residential alternatives are represented as aggregated spatial units (as in conventional residential location models), the variability of dwelling attributes is lost, which may limit the predictive ability and policy sensitivity of the model. This thesis presents a modelling framework for residential location choice that addresses three key challenges: (i) the development of models at the dwelling-unit level, (ii) the treatment of spatial structure effects in such dwelling-unit level models, and (iii) problems associated with estimation in such modelling frameworks in the absence of disaggregated dwelling unit supply data. The proposed framework is applied to the residential location choice context in London. Another important challenge in the modelling of residential locations is the choice set formation problem. Most models of residential location choices have been developed based on the assumption that households consider all available alternatives when they are making location choices. Due the high search costs associated with the housing market, however, and the limited capacity of households to process information, the validity of this assumption has been an on-going debate among researchers. There have been some attempts in the literature to incorporate the cognitive capacities of households within discrete choice models of residential location: for instance, by modelling households’ choice sets exogenously based on simplifying assumptions regarding their spatial search behaviour (e.g., an anchor-based search strategy) and their characteristics. By undertaking an empirical comparison of alternative models within the context of residential location choice in the Greater London area this thesis investigates the feasibility and practicality of applying deterministic choice set formation approaches to capture the underlying search process of households. The thesis also investigates the uncertainty of choice sets in residential location choice modelling and proposes a simplified probabilistic choice set formation approach to model choice sets and choices simultaneously. The dwelling-level modelling framework proposed in this research is practice-ready and can be used to estimate residential location choice models at the level of dwelling units without requiring independent and disaggregated dwelling supply data. The empirical comparison of alternative exogenous choice set formation approaches provides a guideline for modellers and land use planners to avoid inappropriate choice set formation approaches in practice. Finally, the proposed simplified choice set formation model can be applied to model the behaviour of households in online real estate environments.Open Acces

Statistical model on student performance in UTHM by using non-parametric, semi-parametric and parametric survival analysis

Student performance defined as students who are capable to success during their studies. This study explored the use of survival analysis to investigate the performance of Bachelor’s degree students in Universiti Tun Hussein Onn Malaysia (UTHM). The data was collected from the Academic Management Office (AMO), UTHM. The main objective of this study is to estimate the survival rates of students with different entrance qualifications. The study also aim to identify the covariates that dominate the student performance, investigate the performance of Cox model based on the violation of the Proportional Hazard (PH) assumption, compare the model performance by using the survival and Accelerated Failure Time (AFT) models and estimate the time ratio (TR) of student performance in accordance to the selected best model. The survival analysis considered the survival approach such as the Kaplan-Meier (KM) method in the non-parametric method, Cox model in semi-parametric model and survival and AFT models in parametric model. The results revealed that students with STPM-entrance qualification had the highest survival rate compared to Diploma and Matriculation holders. The Cox model in the semi-parametric model identified the GPA, entrance qualification and course as the significant covariates to be included in the study. Faculty covariate was excluded since the p-value insignificant at 90% significance level. The result provided by the Cox model violated the PH assumptions. Then, the performance of the Cox model is less accurate. The invalidation performance of Cox model prompted the need to conduct other parametric survival and AFT models to produce more precise results. As a conclusion, the Log-normal AFT model is the best alternative model to estimate student performance in UTHM and other similar higher educational institution

Efficient access pricing and endogenous market structure

We analyse a (differentiated good) industry where an incumbent firm owns a network good (essential input) and faces potential competition in the (downstream) retail market. Unlike the traditional approach, we consider a scenario where the decision to compete or not in the downstream segment is endogenous, and this decision depends on the particular mechanism designed by the utilitarian regulator. We assume that the technology of the potential entrant is private information. We derive the efficient (Ramsey) prices and access charge taking the impact of a non-discriminatory mechanism on entry decision into account. We assert that the optimal pricing formula must include a Ramsey term that is inversely related to the "modified" superelasticity of the retail good under consideration. We further show, under unknown cost, that there might be "excess" or "too little" entry compared to the socially optimal level.non-discriminatory access, endogenous competition, modified superelasticity

Threshold Accepting for Credit Risk Assessment and Validation

According to the latest Basel framework of Banking Supervision, financial institutions should internally assign their borrowers into a number of homogeneous groups. Each group is assigned a probability of default which distinguishes it from other groups. This study aims at determining the optimal number and size of groups that allow for statistical ex post validation of the efficiency of the credit risk assignment system. Our credit risk assignment approach is based on Threshold Accepting, a local search optimization technique, which has recently performed reliably in credit risk clustering especially when considering several realistic constraints. Using a relatively large real-world retail credit portfolio, we propose a new technique to validate ex post the precision of the grading system.credit risk assignment, Threshold Accepting, statistical validation

Evaluating alternative representations of the choice sets in models of labour supply

During the last two decades, the discrete-choice modelling of labour supply decisions has become increasingly popular, starting with Aaberge et al. (1995) and van Soest (1995). Within the literature adopting this approach there are however two potentially important issues that are worthwhile analyzing in their implications and that so far have not been given the attention they might deserve. A first issue concerns the procedure by which the discrete alternatives are selected to enter the choice set. For example van Soest (1995) chooses (non probabilistically) a set of fixed points identical for every individual. This is by far the most widely adopted method. By contrast, Aaberge et al. (1995) adopt a sampling procedure suggested by McFadden (1978) and also assume that the choice set may differ across the households. A second issue concerns the availability of the alternatives. Most authors assume all the values of hours-of-work within some range [0, H] are equally available. At the other extreme, some authors assume only two or three alternatives (e.g. non participation, part-time and fulltime are available for everyone. Aaberge et al. (1995) assume instead that not all the hour opportunities are equally available to everyone; they specify a probability density function of opportunities for each individual and the discrete choice set used in the estimation is built by sampling from that individual-specific density function. In this paper we explore by simulation the implications of - the procedure used to build the choice set (fixed alternatives vs sampled alternatives) - accounting or not accounting for a different availability of alternatives. The way the choice set is represented seems to have little impact on the fitting of observed values, but a more significant and important impact on the out-of-sample prediction performance.Labour supply, discrete-choice models, quantity constraints, prediction performance