Length of hospital stay at Arak (central Iran) maternity clinics using proposed zero-inflated negative binomial...

The objective of the present article is to suitably model the hospitalization time of the mother and compare the different models. An observational and cross-sectional study was done with a randomized sample of 1600 mothers admitted for delivery at Arak maternity clinics. The hospitalization time was regarded as dependent variable; mother's age and its square, mother's job, having abnormal child, ordinal pregnancy or delivery and its square, number of abortions and its square, number of present children and its square, mother's residency, type of delivery, twice and triplets, all were considered as independent variables. Advanced recent methods of countable data modeling were used. An innovative method was introduced for the data analysis. The modeling of mother's hospitalization time was shown to be the negative binomial model. It was a suitable model due to unequal variance and means of dependent variables for mother's hospitalization time. Having abnormal child, type of delivery (NVD, C and S) and twice delivery were significant variables in this model. More specific models (Zero-truncated Poisson and negative binomial) were shown to be more suitable for the age and its square, having an abnormal child, type of delivery, delivery of twice or triplet which was significant variables in determining mother's hospitalization time. A suitable statistical model for determination and modeling of mothers' hospitalization time was achieved with a simple change of these times. This model included more variables with higher specificity.