Local Box–Cox transformation on time-varying parametric models for smoothing estimation of conditional CDF with longitudinal data

Nonparametric estimation and inferences of conditional distribution functions with longitudinal data have important applications in biomedical studies, such as epidemiological studies and longitudinal clinical trials. Estimation approaches without any structural assumptions may lead to inadequate and numerically unstable estimators in practice. We propose in this paper a nonparametric approach based on time-varying parametric models for estimating the conditional distribution functions with a longitudinal sample. Our model assumes that the conditional distribution of the outcome variable at each given time point can be approximated by a parametric model after local Box–Cox transformation. Our estimation is based on a two-step smoothing method, in which we first obtain the raw estimators of the conditional distribution functions at a set of disjoint time points, and then compute the final estimators at any time by smoothing the raw estimators. Applications of our two-step estimation method have been demonstrated through a large epidemiological study of childhood growth and blood pressure. Finite sample properties of our procedures are investigated through a simulation study. Application and simulation results show that smoothing estimation from time-variant parametric models outperforms the existing kernel smoothing estimator by producing narrower pointwise bootstrap confidence band and smaller root mean squared error.     

The frequency of sexual abuse and depression in a sample of street children of one of deprived districts of Tehran

The purpose of this study was to determine the frequency of sexual abuse and depression among street children who live in a deprived district of Tehran. The researchers used the K-SADS questionnaire and a clinical interview were used to evaluate depression and sexual abuse in 87 street children in Tehran. Eighteen (20.9%) of the children had been sexually abused. Depressed children were 3.2 times more likely to be sexually abused than non-depressed children. Furthermore, 26 girls (86.7%) and 27 boys (48.2%) suffered from depression. The frequency of depression demonstrated a significant association with the father's or breadwinner's history of imprisonment or unemployment. Interventional programs providing education and support should be implemented for street children.     

Divorce and the cost of housing: evidence from Iran

Divorce trend in Iran has become a serious social concern that is suspected of being influenced by rising housing costs in an oil-based economy. Iran has the highest growth rate of divorce among Islamic countries in the Middle East and North Africa region. Using data from 30 provinces of Iran from 2002 to 2010, this paper examines the relationship between housing costs (house prices and rents) and divorce rate, controlling for other macroeconomic variables such as unemployment, inflation, and education in addition to regional, cultural, traditional, and conventional attitudes toward divorce. By applying panel fixed-effects and dynamic generalized methods of moments methods, our results suggest that increases in housing costs erode marital stability in Iran. Our main results are also supported when we focus on the shocks in housing costs, using the Vector autoregressive based impulse response and variance decomposition analyses of divorce rates at the national level from 1982 to 2010.     

Evaluating Quality of Life in Urban Areas (Case Study: Noorabad City, Iran)

Quality of urban life (QOUL) has become an important field within urban studies. The increased level of attention to this topic is due to the increasing importance of QoL studies in monitoring public policies and in the role they can play as effective tools in urban management and planning. The main objective of this study is to measure the QOUL in the town of Noorabad in Iran, using subjective and objective indicators. In addition to secondary datasets, this study relies on a perception survey of households in the selected city. Based on an 11-point Likert scale, the mean of the overall life satisfaction of the respondents was found to be 6.06. At the same time, it has been found that satisfaction from employment opportunities is lowest among all other indicators. The comparison between the subjective and objective QoL in Noorabad indicated that 25 % of the households are in a state of well-being, 30.1 % are in a state of deprivation, while 24.4 % are in dissonance and 20.4 % are in a state of adaptation. Although correlation between objective and subjective dimensions of the QoL has not been found to be high, in general, the findings of this study reveal the importance of simultaneous studying of both objective and subjective dimensions of QoL. Results and findings of this study will be useful in designing and implementing future policies in the town of Noorabad.