Control charts for monitoring the median in non-negative asymmetric data

Statistical Methods & Applications - Control charts are commonly used for monitoring the mean of processes. However, there are practical applications in which asymmetric data are the standard....     

The problem of multiple causation in population analysis, with particular reference to the poplygamy-fertility hypothesis

The hypothesis that polygyny is associated with higher fertility than monogamy was evaluated. An assessment of previous studies and of the results of a 1966-1967 study comparing the fertility levels of polygynously and monogamously married women in a rural and an urban population in Nigeria lead to the conclusion that the hypothesis was useless. The hypothesis was judged to be useless because 1) fertility rates are the product of multiple influences; 2) it is too difficult to separate out these multiple influences, given the variability involved in polygynous practices and the inadequates of the data; and 3) the influence of polygyny on fertility is too slight to take into account. In the Nigerian study, the fertility of 2742 monogamously married women was compared with the fertility of 1261 polygynously married women. Preliminary analysis revealed that the fertility rate was higher for polygynously married women; however, when marriage duration was controlled, there was no significant differences between the fertility rates observed for the polygynously and monogamously married women living in rural areas nor those living in urban area.     

Separate Ratio Estimators for the Population Variance in Stratified Random Sampling

We propose separate ratio estimators for population variance in stratified random sampling. We obtain mean square error equations and compare proposed estimators about efficiency with each other. By these comparisons, we find the conditions which make proposed estimators more efficient than others. It has been shown that proposed classes of estimators are more efficient than usual unbiased estimator. We find that separate ratio estimators are more efficient than combined ratio estimators for population variance. The theoretical results are supported by a numerical illustration with original data. A simulation study is also carried out to investigate empirical performance of estimators.     

Determinants of contraceptive switching behavior in rural Sri Lanka

This study examines the influence of a selected set of determinants of contraceptive method switching in rural Sri Lanka. Of interest is the question of how change in contraceptive practice at the individual level can account for patterns observed at the aggregate level. Based on calendar data on contraceptive use over a 3-year period, collected for more than 3,000 married women in a 1986 survey, the multivariate analysis shows that women who attain all or a significant proportion of their desired fertility tend to switch to more effective methods. Women who experience method failure tend to switch methods, usually to a type that is more effective. The woman's background determinants of age and education have small but significant effects on method switching, whereas the effect of household economic well-being is not significant. There is strong indication that rural couples are practicing contraception in a nonrandom fashion, switching methods in accordance with changes in their fertility motivations and contraceptive experience.     

A Critical Analysis of Australian Television Coverage of Election Opinion Polls

Much recent attention has focused on the nature and possibleeffects of media coverage of opinion polls. Accordingly, thisarticle reports the results of a detailed critical analysisof Victorian television news coverage of election opinion pollsduring the 1980 Australian federal election campaign. Five aspectsof the coverage were analyzed: its extent, focus, completeness,accuracy, and critical balance. The results of the study indicatethat the coverage was seriously, perhaps irredeemably, flawed     

TESTING FOR EFFICIENCY IN LOTTO MARKETS

State-sponsored lotto games, because they are pari-mutuel and because jackpots with no winner are rolled over into the next drawing, present an excellent opportunity to test for market efficiency. Using data from Massachusetts, Kentucky, and Ohio, we investigate bettors' responses and test for weak-form efficiency. Lotto bets do not have positive net expected returns, thus weak-form efficiency exists. To evaluate strong-form efficiency we utilize the concept of a rational expectations equilibrium. We find that in general lotto bettors' decisions to play generate a level of sales that conform to their original forecasts of expected value.