Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Regression analysis of overdispersed correlated count data with subject specic covariates
AU - Solis-Trapala, Ivonne L.
AU - Farewell, Vernon T.
PY - 2005
Y1 - 2005
N2 - A robust likelihood approach for the analysis of overdispersed correlated count data that takes into account cluster varying covariates is proposed. We emphasise two characteristics of the proposed method: That the correlation structure satises the constraints on the second moments and that the estimation of the correlation structure guarantees consistent estimates of the regression coecients. In addition we extend the mean specication to include within- and between-cluster eects. The method is illustrated through the analysis of data from two studies. In the rst study, cross-sectional count data from a randomised controlled trial are analysed to evaluate the ecacy of a communication skills training programme. The second study involves longitudinal count data which represent counts of damaged hand joints in patients with psoriatic arthritis. Motivated by this study, we generalize our model to accommodate for a subpopulation of patients who are not susceptible to the development of damaged hand joints.
AB - A robust likelihood approach for the analysis of overdispersed correlated count data that takes into account cluster varying covariates is proposed. We emphasise two characteristics of the proposed method: That the correlation structure satises the constraints on the second moments and that the estimation of the correlation structure guarantees consistent estimates of the regression coecients. In addition we extend the mean specication to include within- and between-cluster eects. The method is illustrated through the analysis of data from two studies. In the rst study, cross-sectional count data from a randomised controlled trial are analysed to evaluate the ecacy of a communication skills training programme. The second study involves longitudinal count data which represent counts of damaged hand joints in patients with psoriatic arthritis. Motivated by this study, we generalize our model to accommodate for a subpopulation of patients who are not susceptible to the development of damaged hand joints.
KW - generalized estimating equations
KW - marginal model
KW - multivariate negative binomial model
KW - overdispersed correlated count data
KW - subject specific covariates
U2 - 10.1002/sim.2121
DO - 10.1002/sim.2121
M3 - Journal article
VL - 24
SP - 2557
EP - 2575
JO - Statistics in Medicine
JF - Statistics in Medicine
SN - 1097-0258
IS - 16
ER -