Christopher Jackson

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In typical small-area studies of health and environment we wish to make inference on the relationship between individual-level quantities using aggregate, or ecological, data. Such ecological inference is often subject to bias and imprecision, due to the lack of individual-level information in the data. Conversely, individual-level survey data often have(More)
The multi-state Markov model is a useful way of describing a process in which an individual moves through a series of states in continuous time. The msm package for R allows a general multi-state model to be fitted to longitudinal data. Data often consist of observations of the process at arbitrary times, so that the exact times when the state changes are(More)
Behavioural ecology is rife with examples of prey animals that are able to adjust the intensity of their anti-predator response to match background risk levels. Often, preys need experience with predators before they will invest in costly anti-predator responses. This means that prey animals often fail to respond to predators during their first encounter.(More)
OBJECTIVE Previous studies have evaluated the cervical range of axial rotation during simulated driving conditions. The goals of this pilot study were to describe cervical spine rotation during in-car driving and determine the percentage of time outside neutral neck rotation and peak cervical axial rotation angles that the subjects adopted during various(More)
Simulation study One aim of this study is to assess the extent of contextual, or area-level, socio-demographic effects on cardiovascular hospitalisation. It is not generally possible to distinguish between a contextual and underlying individual effect if only the area-level mean of the aggregate covariate is available. However, our data are more detailed.(More)
Coastal and hydrologic applications of Envisat Advanced Synthetic Aperture Radar (ASAR) imagery have been developed and are being demonstrated in a near-real-time applications demonstration environment in Alaska and the Gulf of Mexico. Applications include ocean surface winds for weather and storm forecasts, vessel positions for fisheries monitoring and(More)
A multi-state model expresses the movement of an individual between a finite set of states. It is most commonly used in the form of a Markov model, where the movement follows a Markov process. It can be seen as an extension of survival or time-to-event models, where there are several events. A major application of multi-state models is investigating the(More)