title: Sufficient Sample Size and Power in Multilevel Ordinal Logistic Regression Models.
abstract: For most of the time, biomedical researchers have been dealing with ordinal outcome variable in multilevel models where patients are nested in doctors. We can justifiably apply multilevel cumulative logit model, where the outcome variable represents the mild, severe, and extremely severe intensity of diseases like malaria and typhoid in the form of ordered categories. Based on our simulation conditions, Maximum Likelihood (ML) method is better than Penalized Quasilikelihood (PQL) method in three-category ordinal outcome variable. PQL method, however, performs equally well as ML method where five-category ordinal outcome variable is used. Further, to achieve power more than 0.80, at least 50 groups are required for both ML and PQL methods of estimation. It may be pointed out that, for five-category ordinal response variable model, the power of PQL method is slightly higher than the power of ML method.
authors.affiliation: Department of Statistics, Islamia College University, Peshawar, Pakistan.
authors.forename: Sabz
authors.identifier: 0000-0002-9702-9023
authors.initials: S
authors.lastname: Ali
authors.affiliation: Department of Statistics, Islamia College University, Peshawar, Pakistan.
authors.forename: Amjad
authors.initials: A
authors.lastname: Ali
authors.affiliation: Department of Statistics, Abdul Wali Khan University Mardan, Khyber Pakhtunkhwa, Pakistan.
authors.forename: Sajjad Ahmad
authors.initials: SA
authors.lastname: Khan
authors.affiliation: Department of Statistics, Shaheed Benazir Bhutto Women University, Peshawar, Pakistan.
authors.forename: Sundas
authors.initials: S
authors.lastname: Hussain
mesh_terms: D000465:Algorithms; D035843:Biomedical Research / Q000379:methods* / Q000592:standards; D003198:Computer Simulation; D003625:Data Collection; D003627:Data Interpretation, Statistical; D006801:Humans; D016013:Likelihood Functions; D008288:Malaria / Q000628:therapy; D015233:Models, Statistical; D055361:Multilevel Analysis / Q000379:methods; D012044:Regression Analysis; D015203:Reproducibility of Results; D012107:Research Design; D018401:Sample Size; D013223:Statistics as Topic; D016896:Treatment Outcome; D014435:Typhoid Fever / Q000628:therapy