in this paper, by using the survival models, survival functions for the time from birth to the event of using formula (i.e. the time that baby in fed by breast milk) in urban and rural areas of takestan (iran, winter 1998) are reported. later the relation between the mentioned time and some factors are also discussed. the kaplan-meire method and cox regression are used in this paper as well. 48...

conclusions the use of smoothing methods helps us to eliminate non-linear effects but it is more appropriate to use cox proportional hazards model in medical data because of its’ ease of interpretation and capability of modeling both continuous and discrete covariates. also, cox proportional hazards model and smoothing methods analysis identified that age at diagnosis and tumor size were indepe...

background: northern regions of iran have been encountered to dominate malignancies of gastrointestinal (gi) tract. we came to examine the total excess mortality due to the gi cancer in mazandaran province. methods: socio-demographic and clinical data of 484 patients with gi cancer collected during the years 1990-1991were available from babol cancer registry. patients were followed up for 15 ye...

background: in recent years, the study of birth intervals has been a main determinant of the levels of fertility in the populations, as it is associated with rates of fertility and population growth. objective: the purpose of this study was to firstly apply survival analysis for modeling of first birth interval and secondly to explore its determinants. materials and methods: in a cross sectiona...

background: increasing the complexity in modern radiotherapy techniques have increased the delivery time lowering consequently the treatment efficacy. through simulating the delivery time delay encountered in such techniques, its’ effect on two cancer cell lines and the compensating doses given to prevent such effect was investigated. materials and methods: f10b16 and 4t1 cancer cell lines were...

background: peritoneal dialysis is one of the most prevalent types of dialysis prescribed to the patients suffering from renal failure. studies on the factors affecting the survival of these patients have mainly used log-rank test and cox analysis. the present study aimed to investigate the risk factors affecting short- and long term survival of patients on continuous ambulatory peritoneal dial...

background : gastric cancer is the one of the most prevalent reason of cancer-related death in the world. survival of patients after surgery involves identifying risk factors. there are various models to detect the effect of risk factors on patients’ survival. the present study aims at evaluating these models. methods : data from 330 gastric cancer patients diagnosed at the iran cancer institut...

the data set employed in this study was comprised of a number of 6,800 records of lamb’s longevity and their survival rate, collected from 1989 through 2009, from the lori-bakhtiari experimental flock at the shooli station in shahrekord, iran. the data were analyzed using linear models and proportional hazard models with weibull function. these models included fixed factors and direct additive ...