In many maintenance treatment trials, patients are first enrolled into an open treatmentbefore they are randomized into treatment groups. During this period, patients are followedover time with their responses measured longitudinally. This design is very common intoday's public health studies of...

Missing problem is very common in today's public health studies because of responses measured longitudinally. In this dissertation we proposed two latent variable models for longitudinal data with informative missingness. In the first approach, a latent variable model is developed for the...

Quality improvement (QI) processes in nursing homes are highly variable and often ineffective. This study evaluated an innovative QI process to reduce pressure ulcers (PUs) in a nursing home with a high rate of PUs

Several studies have previously documented the existence of a perception gap -- the extent to which quality-of-life ratings provided by nursing home residents and caregivers diverge. In this study we use Helson's adaptation-level theory to investigate three types of antecedents: (a) focal...

Objective: To determine if educating nursing home staff about pressure ulcer prevention reduces the differential risk of pressure ulcer development in black and white nursing home residents. Design: Subanalysis of a study designed to monitor the emergence of all pressure ulcers in nursing home...

Frailties models, an extension of the proportional hazards model, are used to model clustered survival data. In some situations there may be competing risks within a cluster. When this happens the basic frailty model is no longer appropriate. Depending on the purpose of the analysis, either the...

The joint effect of several variables is a prevailing statistical concept in biology. The public health importance of developing methods to better assess joint effects is evident when studying gene combinations that function together to produce a disease phenotype, or biomarker pairs that...

Receiver Operating Characteristic (ROC) analysis is one of the most widely used methods for summarizing intrinsic properties of a diagnostic system, and is often used in evaluation and comparison of diagnostic technologies, practices or systems. These methods play an important role in public...

Many medical studies collect biomarker data to gain insight into the biological mechanisms underlying both acute and chronic diseases. These markers may be obtained at a single point in time to aid in the diagnosis of an illness or may be collected longitudinally to provide information on the...

Longitudinal censoring is a common artifact when evaluating biomarkers and an obstacle to overcome when jointly investigating the longitudinal nature of the data and the impact on the survival prognoses of a study population. To fully appreciate the complexity of this scenario one has to devise...