The aim of the study was to determine age, period, and cohort effects on trend of alcohol and drug use in the students of Tehran University of Medical Sciences from 2006 to 2009. Between 2006 and 2009, the students of Tehran University of Medical Sciences were surveyed annually using a structured self-administered and anonymous questionnaire. Intrinsic estimator, which is a new method for resolving linear dependency between age, period, and cohort in linear regression models, was used for data analysis. In the present study, in the descriptive method, the prevalence of alcohol consumption increased in males and females with an increase in age. The prevalence of illicit drug use was higher in 2007 in comparison with other periods for males and females. In the analytical method (intrinsic estimator), there were no age, period and cohort effects for alcohol and drug use for females. For males, the age effect exhibited an increasing-decreasing-increasing trend and period and cohort effects showed a decreasing trend for alcohol use. As for drug use, the age effect exhibited gradual increases. The period effect displayed an increasing-decreasing trend and the cohort effect exhibited an increasing-decreasing-increasing trend. The IE method showed no age, period and cohort effects for alcohol and drug use in females. The prevalence of drug and alcohol use increased with an increase in age in males. The high prevalence of drug use could be due to easy accessibility and low price of drugs.

The aim of this study was to compare the intrinsic estimator method and the age, period and cohort accounting model used for identifying age, period, and cohort trends in incidence, prevalence, and mortality rates.
The data of 2 studies " Age, Period, and Cohort Effects on Alcohol and Drug use Among Students of Tehran University of Medical Sciences from 2006 to 2009" and "The Role of Age, Period, and Cohort Effects on Smoking among the Students of Tehran University of Medical Science "were used. First the age, period and cohort accounting model and then The IE method are explained, their advantages and disadvantages are discussed, and their results are compared.
Both methods showed an increasing, decreasing, and increasing trend for age, cohort, and cohort effect for the prevalence of smoking. IE could predict a preventing effect for an early age factor for smoking. In the descriptive model, a decreasing trend was seen from old cohorts to younger cohorts in nearly all age groups. However, the IE method did not show any cohort effects for alcohol consumption in female studnets.
Currently, the IE method is the best method for solving linear dependence between three variables of age, birth cohort, and period in this type of studies. However, researchers should use it with caution because it has many pitfalls.

In this paper, the behavior of households’ consumption expenditures is investigated in the life cycle model as one of the determinant factors of welfare. For this purpose, consumption expenditures were decomposed into age, cohort and time effects by using Deaton (1997) model. The main focus of this model is to explain the intergenerational behavior of consumption. Survey of long-term consumption expenditure through comparison of different generations represents valuable information about quality of individual and household's life during time. This objective is fulfilled by constructing pseudo panel that combines twenty nine years of cross-sectional Household Expenditures and Income Surveys from 1984 to 2012. The pseudo panel is constructed with cohorts which are limited to those born between 1926 and 1980. Furthermore, unemployment rate will be reviewed as one of the factors that affect people's expenditures. High unemployment rate and vague perspective of labor market among youth and new generations makes this review much more important. Results indicate that consumption expenditures of the younger cohorts relative to their predecessors at the same age increased, but the increasing rate is decreasing. The age effects results indicate that expenditures rise until age 50 and after that are relatively flat until age 60 and then declining gently. The year effects show that life cycle expenditure is consistent with economic changes during different years in Iran. The results of unemployment rate show that between age 25 and 37 the unemployment rate is falling, and after that it is nearly constant. The results of cohort effects also suggest that in similar ages, there is no significant differences in the unemployment rate of those born between 1926 and 1970 but the cohort effects are rising for cohorts born after 1971.

This cross- sectional study was done to assess the prevalence of chronic cough by age and date of birth (age-period-cohort analysis). Using data from two National Health Surveys in 1991 and 1999 (involving cross-sectional general population samples), we studied all cases of chronic cough recorded during the period of 1991 to 1999 in people aged 2 to 70 years. A birth cohort analysis was performed on the data. Comparison with earlier surveys showed that the prevalence of chronic cough had fallen from 4.5% to 1.8%. Age-period-cohort analyses of the age effect revealed that prevalence rate of chronic cough increased with age but in every age group it actually decreased after the 8-year period. The fact that different trends are observed in cross-sectional and cohort data points to a strong cohort effect. the prevalence of chronic cough is strongly determined by a person’s year of birth. Also for any given age group, prevalence rates were lower in younger compared to older cohorts.

Few Studies have studied the role of generational change (cohort effect), as an important demographic variable, within demand system, whereas generational changes can impact on elasticities, expenditure share as well as expenditure level. Therefore, to examine the impact of the demographic variables in addition to the economic and social variables on purchase and consumption of the nine food groups, this study uses a censored Quadratic Almost Ideal Demand System (QAIDS) with age-period-cohort (APC) variables. For this purpose, the pooled data of 337151 urban household's and 330501 rural household's for years 1363-93 was used. The results show age (aging population), generational change and period shocks impact on both food adoption and food consumption.
Few Studies have studied the role of generational change (cohort effect), as an important demographic variable, within demand system, whereas generational changes can impact on elasticities, expenditure share as well as expenditure level. Therefore, to examine the impact of the demographic variables in addition to the economic and social variables on purchase and consumption of the nine food groups, this study uses a censored Quadratic Almost Ideal Demand System (QAIDS) with age-period-cohort (APC) variables. For this purpose, the pooled data of 337151 urban household's and 330501 rural household's for years 1363-93 was used. The results show age (aging population), generational change and period shocks impact on both food adoption and food consumption.

To date, few studies looked upon obesity and overweight in children and adolescents through the 3 different temporal dimensions of age, period, and cohort. The current study aimed at evaluating the trends of these health issues among children under 19 years old using the age-period-cohort (APC) analysis.
Data gathered through 5 cross sectional studies including 2 national health surveillance (1990 - 91 and 1999), and 3 CASPIAN surveys (2003, 2009, and 2011). Subjects were classified by their body mass index (BMI) into 3 groups of normal (BMI A total of 80,698 children and adolescents under 19 years old, including 40,419 (50.09%) males and 40,279 (49.91%) females, were evaluated. The prevalence of obesity decreased progressively by age in males and females with minor discrepancies. It increased from 1990 to 2009 in both genders, but from that point on remained quite constant in males and dropped significantly in females. The prevalence of obesity was steady in earlier birth cohorts, but increased significantly after the birth cohorts from 1986 to 1990.
Environmental factors and social stresses during neonatal and infantile periods (birth cohort effect) along with other variables influencing the children later in their lives (period effect) affect the prevalence of overweight and obesity substantially. Moreover, a decrease in the prevalence of obesity and overweight was observed by age increase (age effect).

One of the most fundamental statistical studies which are carried out in most countries to assess the various social and economic programs is the study of the household budget survey. By this we can discover the distribution of household income and expenditure and economic changes of individuals and families during the life cycle. Information of the investment patterns of the households in different age groups and investigating its changes during different years are important economic issues at micro and macro data level that can analyze the economic behavior and investment pattern of households. This paper is a descriptive and statistical research based on the annual urban and rural Household Expenditure and Income Survey (HEIS) data during 1999- 2011 which evaluates the change of household investment and analyzes the change trends in construction and agriculture sectors. In this paper in addition to descriptive analysis of household's investment trends, the estimate of cohort investment pattern by using Dayton model1 is drawn. In this model, the household expenditure on investment sector decomposes into year, age, and cohort effects in which the possibility of investing the cohort investment pattern of life cycle is provided. Also, to determine the effective factors on household's investment, using logistic model, the effect of some household and head of household characteristics on household investment expenditure is discussed.

Suicide is one of the psychosocial problems in Lorestan Province due to its socio-cultural and economic structure. The aim of this study was to investigate the effect of age group, time period, and birth cohort on the suicide incidence in Lorestan Province during the 2006-2015.
  In this study, to overcome the identifiability problem, the Carstensen approach and natural cubic smoothing character were used in age-period-cohort models (APC). Cohort effect was calculated as the relative rate from the 1984 reference cohort for men and 1987 cohort for women. The period effect in both sexes constrained to be relative to 1390 and to be 0 on average with 0 slope. The best APC model for both sexes was the models with "AC-P" parameter, 7 knots, and natural splines for men and B splines for women. All analyses were performed using the R software with Epi package.
  The age effect showed that the highest suicide incidence rate was seen in the elderly. Two strong birth cohort effects were observed, one increasing one in the 1980 cohort and one decreasing one in 1991 cohort. The most significant period effect was seen in men in 2011.
  The effects of 1991 and 1980 birth cohorts could be due to the consequences of imposed war in Iran. The three economic phenomena, oil price change, increased divorce rate, and increased unemployment rate can be effective in the emergence of the period effect in year 2011.

Economic welfare is one of fundamental issue in every countrys economy. In recent years implementation of targeted subsidies has various effects on the economy and household expenditure. In this paper is to examine the welfare effects of subsidies targeting on household expenditure. For this purpose, in this study, usingthe Stata software and Dayton & Paxon method (1997), the model of life cycle of households in the provinces of Tehran and Isfahan has been investigated. The results of household consumption expenditure separation in relation to the effects of time show that households consumption expendituretrend in Tehran is regular, However, consumption expenditures of households in Isfahan were regular before subsidies targeting, but after that they were irregular. Meanwhile, consumption expenditures of Isfahan households before targeting subsidies in some years (2004, 2007 and 2010) were lower than those in Tehran and in one year (2003).In addition, the average consumption expenditure of households in Isfahan province during the whole period, as well as after targeting the subsidies washigher than the households in Tehran province, and the average consumption expenditures of their households during the whole period, but not significant in Tehran province.