Robustness of confidence intervals for scale parameters based on m-estimators

The robustness of confidence intervals for a scale parameter based on M-esimators is studied, especially in small size samples. The coverage probablity is used as measure of robustness. A theorem for a lower bound of the minimum coverage probability of M-estimators is presented and it is applied in order to examine the behavior of the standard deviation and the median absolute deviation, as interval estimators. This bound can confirm the robustness of any other scale M-estimator in interval estimation. The idea of stretching is used to formulate the family of distributions that are considered as underlying. Critical values for the confidence interval are computed where it is needed, that is for the median absolute deviation in the Normal, Uniform and Cauchy distribution and for the standard deviation in the Uniform and Cauchy distribution. Simulation results have been achieved for the estimation of the coverage probabilities and the critical values.     

New Light on the Remittances‐Poverty‐Health Nexus in Macedonia

Macedonia receives about 10 per cent of GDP as cash remittances per year while a third of the population faces poverty. The study aims to investigate whether remittances improve the poverty and health of individual remittance‐receivers in Macedonia. To that end, we rely on the 2008 Remittances’ Survey and a sequential structural model linking remittances to social indicators. We find that remittances have a significant effect oto consumption, in particular health consumption, hence contribute to reducing poverty. In turn, improved health consumption significantly reduces the incidence of bad health among receivers. This finding lends support to the claim that remittances serve an informal social protection in Macedonia.     

Remittances as a Shield to Vulnerable Households in Macedonia: The Case When the Instrument is Not Strictly Exogenous

The objective of this article is to investigate whether remittances sent to Macedonia have a role to play for shielding vulnerable households, by highlighting the importance of a strictly exogenous instrument in an IV context. Results suggest that remittance‐receiving households have, on average, a 20.1 per cent lower vulnerability than non‐receiving ones. However, if one has a reasonable belief that vulnerability and the instrument are determined simultaneously, or are directly correlated due to the existence of a third unobservable factor, then the shielding effect of remittances for vulnerable households remains up to the ninth percentage of direct influence and with a reducing magnitude, and then disappears.     

Hope and Adaptation to Old Age: Their Relationship with Individual-Demographic Factors

This study examined the relationship between hope as disposition, adaptation to old age, and individual-demographic factors. One hundred and fifty older adults, aged 60–93 years old, completed the Adult Dispositional Hope Scale developed by Snyder et al. [1991, Journal of Personality and Social Psychology, 60, pp. 570–585], and the Adaptation to Old Age Questionnaire developed by Efklides et al. [2003, European Psychologist, 8, pp. 178–191]. Factor analyses revealed 2 factors for hope, “Pathways Thought” and “Agency Thinking”, and 4 factors for adaptation to old age, “Health Comparison”, “General Adaptation/Self-Efficacy”, “Self-Control”, and “Generativity”. Regression analyses showed that hope as pathways thought predicted all factors of adaptation, whereas hope as agency thinking predicted only “General Adaptation/Self-Efficacy” and “Self-Control”. There were also some effects of gender, education, marital status, place of residence, and health status on specific aspects of adaptation to old age.     

The 50% breakdown point in simultaneous M-estimation of location and scale

Received: November 8, 1999; revised version: March 13, 2000