A study of the correlation bias of unrecorded events by two independent enumeration systems

Summary In this paper the allegation that, when using the Chandrasekar-Deming technique with two independent enumeration systems to record the incidence of vital events and migrations, each individual system misses the same type of event is investigated. If this correlation bias were to occur frequently enough, it could result in a serious underestimation of a given type of event. Using vital events and migrations data derived from a longitudinal survey conducted in Liberia between 1969 and 1973, the estimated number of recorded events is tabulated into homogeneous groups that are demonstrated to affect omission rates. The proportion of missed eyents is computed separately for each enumeration system, and the presence or absence of a significant correlation mathematically determined. The results of this study suggest that no significant correlation could be demonstrated in the type of birth, death or infant death that was commonly missed by each individual enumeration system. This indicates that the omission of a birth, death or infant death was apparently a random occurrence as far as the individual casefinding systems were concerned. The authors conclude that any underestimation of vital events from this type of correlation bias may not be as serious as originally imagined. In contrast to this observation, the omission of particular types of migrations by each enumeration system was apparently not a random occurrence, but was associated with the direction of migration. This implies that selected migration rates in the liberian survey were probably understated and this could happen in other longitudinal surveys, unless specific precautions are taken to avoid it.     

Ethnographic perspectives on the enumeration of aboriginal people in remote Australia

This paper compares population counts and age distributions from the last two Australian Bureau of Statistics (ABS) enumerations of the Aboriginal population of Aurukun, Cape York Peninsula, with the results of detailed ethnographic surveys of the same population at similar points in time. This reveals substantially lower numbers for the ABS counts, particularly of young adults and children. Reasons for this discrepancy are sought in the ethnographic realities of remote indigenous communities and an alternative methodology for Aboriginal enumeration in remote regions is suggested.     

The completeness of enumeration in the 1973 census of the population of Colombia

The effort is made to determine the true size and distribution by age and sex of the population of the Republic of Colombia in October 1973. After initially arriving at estimates of the levels of fertility and mortality during the intercensal period and then correcting the 1964 census population for age misreporting and selective undernumeration of males, a hypothetical populaiton corresponding to October 1973 is constructed. Comparing the constructed population with the population observed in the census yelds an estimate of completeness of enumeration in 1973 that is relative to the enumeration of females in 1964. This estimate is obtained under the assumption that net international migration during the period was of negligible importance. As there is reason to believe that this is not a valid assumption and upon examining the limited amount of evidence available, speculaitons are made concerning the amount of net out-migration to have occurred during the 1964-1973 period and the size of the coresponding modificaiton in the estimate of completeness of enumeration. After adjusting for underenumeration of males in 1964 and neglecting the impact of international migration, a theoretical 1973 census population of 23,201,000 was estimated. Apart from the total number of people enumerated, the information that was analyzed from the advance sample appears to be of good quality, at least in relation to prior censuses. The estimates of fertility and mortality reveal an important decline in Colombian fertility. By coming up with separate estimates of infant and childhood and adult mortality, it has been possible to shed new light on the shape and the level of mortality in Colombia. The new Brass method for estimating adult mortality provides reliable results even when mortality has been declining, and there are recognizable distortions in the distribution of the population by age.     

Wives and ex-wives: A new test for homogamy bias in the widowhood effect

Increased mortality following the death of a spouse (the “widowhood effect”) may be due to (1) causation, (2) bias from spousal similarity (homogamy), or (3) bias from shared environmental exposures. This article proposes new tests for bias in the widowhood effect by examining husbands, wives, and ex-wives in a longitudinal sample of over 1 million elderly Americans. If the death of an ex-wife has no causal effect on the mortality of her husband, then an observed association between the mortality of an ex-wife and her husband may indicate bias, while the absence of an effect of an ex-wife’s death on her husband’s mortality would discount the possibility of homogamy bias (and also of one type of shared-exposure bias). Results from three empirical tests provide strong evidence for an effect of a current wife’s death on her husband’s mortality yet no statistically signifi cant evidence for an effect of an ex-wife’s death on her husband’s mortality. These results strengthen the causal interpretation of the widowhood effect by suggesting that the widowhood effect is not due to homogamy bias to any substantial degree.     

A note on measuring the independent impact of family planning programs on fertility Declines

This note critically evaluates recent cross-national studies that estimate the independent effect of family planning programs on the fertility of the developing world. The evaluation demonstrates that past research is biased to produce overestimates of net program impact. A new estimate is derived to account more completely for the effects of the social context and socioeconomic development on fertility. This estimate indicates that 5 percent of the variation in crude birth rate decline for 89 developing countries is due to family planning programs. This is substantially less than past estimates.     

A study on IUD retention by curve-fitting

In order to estimate the demographic impact of IUD, there is a need for estimating IUD retention rates beyond the period of actual observation. This article describes a mixed exponential function for this purpose. With this function of IUD retention, it is possible to estimate the “life expectancy” and “half-life” of an IUD. Another important concept is the “cut-off date”, introduced in estimating the “life expectancy” because in practice no IUD will be worn by a woman forever.     

A sensitivity analysis of the bongaarts-feeney method for adjusting bias in observed period total fertility rates

Our sensitivity analysis shows that the adjusted TFR'(t) using the formula of Bongaarts and Feeney (1998), which assumes an invariant shape for the fertility schedule, usually does not differ significantly from an adjusted TFR"(t) that allows the shape of the fertility schedule to change at a constant annual rate. Because annual changes in the shape of the fertility schedules often are approximately constant except in abnormal conditions, the Bongaarts-Feeney (B-F) method is generally robust for producing reasonable estimates of the adjusted TFR'(t). The adjusted TFR'(t) neither represents any real cohort experiences from the past nor forecasts any future trend. It merely provides an improved reading of the period fertility measure, which reduces the tempo distortion.     

A tale of two provinces

The population program in 2 provinces of the Philippines 1 which has achieved success already and 1 where success is expected ultimately - is described. The Laguna program, launched in 1960, has reduced the annual birthrate to 1.8%, the lowest rate in the country. Governor F.T. San Luis, elected that year, is credited with much of the success of the program. The relatively high standard of living of the people in the province, cooperation of various related agencies, and the consistency and continuity of the program have made for success, despite initial problems with financing, conservative opposition, and interagency confusion. Capiz province is the model family program of the Commission on Population - Total Integrated Development Approach program for the southern region of the country. This program originally worked to develop self-awareness concerning needs and ambitions for the future among the people. When the program got under way in 1975, it stressed training, orientation, and education campaigns. Family planning in Capiz is part of the larger socioeconomic development program.     

Simulating bias in the estimator of labor market discrimination

In this study, the statistical bias in the most widely used estimator of labor market discrimination is investigated. An algebraic expression for the bias is derived and then simulated for a selected set of explanatory variables and model parameters. The results for a large national dataset seem to indicate that when the variables years of schooling and labor market experience are used in earnings functions, the estimator tends to underestimate the actual or true amount of labor market discrimination.     

The influence of catholic schools on the desegregation of public school systems: A case study of white flight in Boston

White flight from public school desegregation can result in educational and residential resegregation which defeat the purpose of desegregation programs. One form of white flight is pupil transfer to private schools, which in major metropolitan areas are predominantly Catholic schools. Unlike residential relocation, transfers to Catholic schools do not effect an increase in residential segregation and they constitute a potentially less permanent loss to the public system than that caused by relocation. Nevertheless, empty seats in area Catholic schools pose a threat to the success of any desegregation program. For the Catholic diocese, the white flight issue creates a complex conflict of interests, involving institutional self-interest and competing claims to moral principles and Church teachings.A case study of Boston indicates that approximately 2,000 students transferred to Catholic schools from the public system, accounting for over 20 percent of white pupil loss to the public system. This occurred despite diocesan policies designed to prevent white flight to Catholic schools. An analysis of political and institutional constraints on policy development and implementation provides a basis for predicting Church response to future desegregation programs in other locations. Suggestions for diocesan programs designed to address desegregation issues are included.This research was conducted as part of a national study of public school desegregation directed by Karl E. Taeuber. Funding was provided by the Institute for Research on Poverty and the Wisconsin Center for Educational Research, both at the University of Wisconsin at Madison. I wish to thank Dr. Taeuber for facilitating this particular study and for helpful comments on an earlier draft. I also wish to acknowledge the valuable assistance of Mary J. McDonald and Roger Hedge of the Massachusetts Department of Education and Rev. Eugene Sullivan, Superintendent of Schools of the Archdiocese of Boston. Conclusions and interpretations presented here are the sole responsibility of the author.     

Reporting of fertility events by men and women in rural Gambia

We conducted a survey of male and female fertility in rural villages in The Gambia and compared men and women's reports of recent pregnancy events in the aggregate and of children ever born for matched couples. Despite widespread polygyny and sex differences in fertility, men's and women's reports were similar. Small sex differences in reports of recent stillbirths and neonatal deaths were found. For matched couples, husbands reported 0.23 more children ever born than their wives on average, but discordant reporting had little effect on recent marital fertility rates. Modeling of discordant reports indicates that fertility reports are more likely to be underestimated by both men and women for their earliest marriages. Reliable fertility data can be collected from men in this population.     

Interspecific competition between two species of Trichogrammatidae III The analytical study on the competition

Summary The experiment was carried out in order to analyze the results of interspecific competition which were mentioned in the previous reports (Sasaba 1964, 1965). The following definite tendencies were obtained and an account was given with regard to the process of competition. (1)T. minutum had a higher reproductive rate thanT. japonicum at a lower density of the parent wasps. (2) The parasitic efficiency ofT. minutum was high as compared withT. japonicum. (3)T. japonicum was consistently superior toT. minutum in the interspecific competition at larval stage. Contribution from the Entomological Laboratory, College of Agriculture, Kyoto University, No. 384.     

Simulating the effect of demographic events on the household composition

The aim of this paper is to measure the effects on household composition of changes in demographic events, e.g. mortality, fertility, marriage, divorce. British household data are taken from the General Household Survey and aged by simulation to 2001 using a ‘Most Likely’ model. Subsequently different assumptions of each demographic event are taken from 1991 so that the effects of perturbations within each event can be studied. Special features of the simulation model are the differentiations between cohabitation and marriage and separation and divorce, and the detailed breakdowns of household types such as lone parents into single and previously married women and men with children aged 0–4, 5–15 and 16 and over.     

Consequences of decriminalization of homosexuality: a study of two Australian states

A comparison between homosexual males in two Australian states, Victoria (prior to decriminalization of homosexuality) and South Australia (eight years after decriminalization), indicated that the consequences of decriminalization did not include an increase in the negative aspects of homosexuality, such as public solicitation or sexually transmitted disease. Findings suggest that as a consequence of decriminalization, the psychological adjustment of homosexual men will increase and sexually transmitted diseases and public solicitation will decrease. These data are tentatively interpreted as indicating that there are few if any negative consequences of decriminalizing homosexuality, and a number of positive consequences.     

A field study of the effect of prebaiting on censusing by the capture-recapture method in a vole population

Summary Populations of the vole,Clethrionomys rufocanus, in a lowland woodlot of Hokkaido were studied for the presence of effects of prebaiting on censusing by the capture-recapture method. A grid of 121 live-traps, spaced 5 m apart, was laid out on each of two plots, one of which alone was prebaited three days long. Owing to very high densities and great trap-efficiency, sufficient and favourable samples could be available for statistical analysis, except the trend of delayed catch for young in sampling. The population on either plot, however, proved to be markedly variable in catchability of unmarked animals in the course of trapping; while the probability of recapture was counted as invariable on the average from day to day, the recapture frequency was different between juveniles, subadults and adults. Needless to say, the catchability was distinctly greater for marked voles than for unmarked ones, whether prebaited or not, through the trapping period, except that the first-day catchability for unmarked ones on the prebaited plot seems not to be significantly lower than that for marked ones. Consequently, it turns out that the prebaiting has almost never helped to eliminate the important bias induced by differential trap-response of marked and unmarked animals; its contribution is only that the catchability for unmarked ones is slightly higher on the part of the prebaited plot on earlier days of the period. In accordance with the heterogeneous catchability, the Γ-form distribution analogous to the geometric could be applied with thorough fitness to the capture frequency in order to estimate the whole populations. The fact that the estimates are reliable, being not at any rate underestimates, was further confirmed by the result of a follow-up work conducted by means of the removal method with wider trap-spacing which brought forth distinct underestimation chiefly referable to unexposure to traps of the partial populations. The subject of unexposure was discussed by laying stress on the relation between minimum range length and trap-spacing. Contribution from JIBP-PT No. 88, carried out by the grant from the expenditure of Education Department to the specific study on “Dynamics of Biosphere”.     

Hemorrhoids during pregnancy: Sitz bath vs. ano-rectal cream: A comparative prospective study of two conservative treatment protocols

Background

Hemorrhoids are a very common ano-rectal condition affecting pregnant females worldwide and representing a major medical and socioeconomic problem. In this paper, we aim to compare the effectiveness of the Sitz bath method with an ano-rectal cream as part of a conservative management protocol to treat hemorrhoids among pregnant Saudi Arabian females.

A comment on the "sixteenth-century population decline in the Basin of Mexico: a systems simulation" by Thomas M. Whitmore

The author comments on an article by Thomas M. Whitmore, entitled "Sixteenth-century population decline in the Basin of Mexico: a systems simulation", which appeared in the Fall 1991 issue of the Latin American Population History Bulletin.