title: Applied shared log-normal frailty Cox-proportional hazard model to evaluating the effect of vitamin A on the rat passive avoidance memory.
abstract: In this research, the Cox-proportional hazard model is used to investigate the effect of various values of vitamin A (3000, 4500 and 6000 IU kg(-1)) and sesame oil on the passive avoidance memory of rats by shuttle box. Present results confirm that various values of vitamin A do not improve the passive avoidance memory of rats (p < 0.05). We found that the animals are clustered (p < 0.001) and applying shared log-normal frailty for clustering improves present results (p < 0.05) such that sesame oil improves the passive avoidance memory task (p < 0.05). Therefore we should consider clustering in the analysis of biological data or we should use cloned animals.
authors.affiliation: Department of Statistics, Shahid Chamran University, Ahvaz, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zadkarami
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D001522:Behavior, Animal / Q000187:drug effects; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D016016:Proportional Hazards Models; D051381:Rats; D014801:Vitamin A / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology*
chemical_list: D014815:Vitamins; D014801:Vitamin A