title: A transition model for ordinal response data with random dropout: an application to the fluvoxamine data.
abstract: Many methods are available to analyze incomplete longitudinal ordinal responses. In this paper a general transition model is proposed for longitudinal ordinal responses with random dropout. Maximum likelihood estimates are obtained for the transition probabilities when there are repeated observations. The likelihood function of the general model is partitioned to make possible the use of existing software to estimate model parameters. Some reduced forms of the model are also considered where for estimation of parameters in these models one has to use numerical optimization methods. The approach is applied to the well-known Fluvoxamine data. For these data, two important results, which have not been previously reported, are obtained: (1) some transition probabilities are estimated to be zero and (2) the model for current response, which conditions on previous response, removes the effects of some covariates that had previously been significant.
authors.affiliation: Department of Statistics, Shahid Beheshti University, Tehran, Iran.
authors.forename: Z Rezaei
authors.initials: ZR
authors.lastname: Ghahroodi
authors.forename: M
authors.initials: M
authors.lastname: Ganjali
authors.forename: D
authors.initials: D
authors.lastname: Berridge
mesh_terms: D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D003627:Data Interpretation, Statistical; D016666:Fluvoxamine / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D016013:Likelihood Functions; D008137:Longitudinal Studies; D008390:Markov Chains; D015233:Models, Statistical; D015337:Multicenter Studies as Topic / Q000706:statistics & numerical data*; D010352:Patient Dropouts / Q000706:statistics & numerical data*; D017367:Selective Serotonin Reuptake Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D016666:Fluvoxamine; D017367:Selective Serotonin Reuptake Inhibitors