Statistical modelling of falls count data with excess zeros

Khan, Asaduzzaman, Ullah, Shahid and Nitz, Jenny (2011) Statistical modelling of falls count data with excess zeros. Injury Prevention, 17 4: 266-270. doi:10.1136/ip.2011.031740

Author Khan, Asaduzzaman
Ullah, Shahid
Nitz, Jenny
Title Statistical modelling of falls count data with excess zeros
Journal name Injury Prevention   Check publisher's open access policy
ISSN 1353-8047
Publication date 2011-08
Sub-type Article (original research)
DOI 10.1136/ip.2011.031740
Volume 17
Issue 4
Start page 266
End page 270
Total pages 5
Place of publication London, United Kingdom
Publisher BMJ Group
Collection year 2012
Language eng
Formatted abstract
Objective To examine the appropriateness of different statistical models in analysing falls count data.
Methods Six count models (Poisson, negative binomial (NB), zero-inflated Poisson (ZIP), zero-inflated NB (ZINB), hurdle Poisson (HP) and hurdle NB (HNB)) were used to analyse falls count data. Empirical evaluation of the competing models was performed using model selection criteria and goodness-of-fit through simulation. Data used were from a prospective cohort study of women aged 40–80 years.
Results Of the 465 women analysed, 330 (71%) did not fall at all. The analyses identified strong evidence of overdispersion in the falls data. The NB-based regression models (HNB, ZINB, NB) were better performed than the Poisson-based regression models (Poisson, ZIP, HP). Vuong tests favoured the HNB model over the NB and ZINB models and the NB model over the ZINB model. Model accuracy measures and Monte Carlo simulation of goodness-of-fit confirmed the lack of fit of the Poisson-based regression models and demonstrated the best fit for the HNB model with comparable good fit for the ZINB and NB models.
Conclusions Falls count data consisting of a considerable number of zeros can be appropriately modelled by the NB-based regression models, with the HNB model offering the best fit. The evaluation procedure presented in this paper provides a defensible guideline to appropriately model falls or similar count data with excess zeros.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
School of Health and Rehabilitation Sciences Publications
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