Farshad Poor Malek, Farid Abolhasani, Mohsen Naghavi, Kazem Mohamad, Reza Madjd-Zadeh, Kourosh Holakooi,
Volume 10, Issue 1 (3-2007)
Abstract
Introduction: Life expectancy is one of the summary measures of population health, whose values and trend of changes over time show the main outcome of health system performance. Estimation of life expectancy is performed with direct or model-based methods. In this study direct estimation of life expectancy for Iran’s population in year 2003 is performed. Materials and Methods: In an ecologic study, for calculation of abridged period life table for 23 out of 28 provinces of Iran in year 2003, numbers of registered deaths for age and sex specific groups in these 23 provinces by death registration system of Ministry of Health (MOH) were used. Undernumeration of over-four year's deaths was estimated and corrected with Brass Growth-Balance method. For mortality rates of under-one and 1-4 years, similar rates from Demographic and Health Survey (DHS) 2000 with live births denominators were substituted. For total number of population of 23 provinces, information from MOH was used. Distribution of population by age and sex was taken similar to that from DHS 2003 results, and also taken as result of graduation of whole country population from 1375 census. Population of these 23 provinces was equal to 73% of total population of country in year 2003. Life expectancy was estimated by age and sex with the obtained population and death numbers. It was assumed that distributions of population and death in 23 provinces were similar to those for the whole 28 provinces of Iran in year 2003 and hence, the estimated life expectancy for 23 provinces is equal to that for all 28 provinces in 2003. Sensitivity of the results to assumptions was analyzed. Confidence intervals were calculated with Monte Carlo method. Results: Life expectancy at birth was estimated as 71.56 years for total population (95% CI: 71.52 – 71.62), 70.09 years for males (70.02 – 70.16), and 73.17 (73.10 – 73.24) for females of Iran in year 2003. Sensitivity of results to assumptions was less than 0.5%. Conclusion: Values of life expectancy estimates for year 2003 with direct method are higher than those based on statistical modeling approaches performed by Statistical Center of Iran and by different United Nations agencies, due to difference in estimation methods for age and sex specific mortality rates.
Reza Pakyari, Mohammad Rafiei, Somayeh Abolhasani,
Volume 19, Issue 6 (9-2016)
Abstract
Background: The failure time of permanent tooth is of the form of interval censored since the exact time of tooth decay is not available and it is only known that tooth decay occurs between two consecutive visits. There are a few techniques available in the literature for the problem of goodness-of-fit for interval censored data. In this paper, we propose a new goodness-of-fit testing procedure for interval censored data and employ this for the failure time of the first permanent molar tooth (sixth tooth) data.
Materials and Methods: Two methods of goodness-of-fit for interval censored data that are based on randomly generated data from each interval and averaging over the test statistics or over the p-values are employed for the failure time of the first permanent molar tooth data.
Results: The mean of the failure time of the first permanent molar tooth is found to be at 95 months. The p-values of the two goodness-of-fit testing procedures for the Weibull, log-normal and gamma models are calculated.
Conclusion: By comparing the p-values, the log-normal model is considered as the best model to describe the failure time of the first permanent molar tooth data.
