A study into drug-trying behaviour among young people in England : categorical analysis models in the Presence of missing data

Chan, Henry and Costain, Deborah and Ridall, Gareth (2019) A study into drug-trying behaviour among young people in England : categorical analysis models in the Presence of missing data. PhD thesis, Lancaster University.

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Abstract

This research reviewed the "Smoking, Drinking and Drug Use among Young People in England" 2010 survey (the Year 2010 Survey) study in terms of its data collection, processing and analysis. The research aim was to gain increased understanding of young people’s drug-trying behaviour in England through appropriate handling of missing data, as well as, to build upon the previous work done, developing and applying statistical methodologies for analysis of multivariate categorical data collected by the Year 2010 Survey study. The main work done in this research included: (1) modifying the original data set to arrive the useful working data set; (2) conducting exploratory data analysis with the working data set to identify direction for further empirical investigation; (3) properly handling the missing data problem in the working data set and (4) developing and applying advanced statistical methodologies to further analyse the working data set. Apart from supporting the main findings of the Year 2010 Survey study that smoking, drinking and some drug-related socio-demographic covariates were positively associated with the students’ drug-trying behaviour, additional significant results found by the univariate logistic regression models, log-linear analysis models, two-parameter item response theory models and latent class analysis models reported that (1) the 15 drugs were highly and positively associated with each other and each drug exerted different extent of influences on the students’ drug-trying behaviour and (2) generally, students’ drug-trying behaviour could be further explained by numerous smoking, drinking and drug related socio-demographic factors at different extent. These additional findings contributed to a deeper understanding of the drug use problem, added evidence to the drug related research literature and provided helpful guidance on formulating policies to combat against drug use problem in England. Another contribution of this research was the development of a new methodology for backward elimination of latent class analysis models which provided a more thorough evaluation of the optimal number of latent class and covariate elimination from saturated model.