Child survivorship estimation: methods and data analysis

"The past 20 years have seen extensive elaboration, refinement, and application of the original Brass method for estimating infant and child mortality from child survivorship data. This experience has confirmed the overall usefulness of the methods beyond question, but it has also shown that...estimates must be analyzed in relation to other relevant information before useful conclusions about the level and trend of mortality can be drawn.... This article aims to illustrate the importance of data analysis through a series of examples, including data for the Eastern Malaysian state of Sarawak, Mexico, Thailand, and Indonesia. Specific maneuvers include plotting completed parity distributions and 'time-plotting' mean numbers of children ever born from successive censuses. A substantive conclusion of general interest is that data for older women are not so widely defective as generally supposed."     

Age-specific survivorship analysis ofHeliothis spp. Populations on cotton

Summary Population dynamics ofHeliothis virescens (F.) andHeliothis zea (Boddie) (Lepidoptera: Noctuidae) eggs and larvae were studied for two years in a small plot of cotton,Gossypium hirsutum (L.). Due to morphological and ecological similarities, the pooledHeliothis population was considered for most of the analyses. Two generations ofHeliothis eggs and larvae were completed during each year. Stage recruitment was estimated for the eggs and larval instars 2–6, and recruitment variances were estimated by a Monte Carlo method. A modified form of the Weibull distribution was developed and used as a model to characterize survivorship curves for each of the fourHeliothis generations. A Type I survivorship curve (mortality rate increasing with age) was inferred for both Generation 1 (early season) data sets, whereas a Type II survivorship curve (mortality rate constant and thus independent of age) was inferred for both Generation 2 (late season) data sets. The shapes of the survivorship curves for the individualH. virescens andH. zea populations were inferred to be the same as those for the pooled populations. Analysis of the contributions of various factors toHeliothis stage-specific mortality indicated that natural enemies (predators and parasites) and the availability of food for larvae were responsible for between-generation differences in survivorship patterns.     

Anopheles subpictus Grassi: Observations on survivorship and population size using mark-release-recapture and dissection methods

Summary A mark-release-recapture experiment to estimate population survivorship and absolute size was performed with wild-caughtAn. subpictus adults at the village of Khano-Harni, Lahore District, Punjab Province, Pakistan during September 1978, the end of the monsoon rainy season, when temporal population abundance was maximized. Daily survival rate estimated from the recapture sequence of marked adults was low, males=0.192 and females=0.343. Survivorship for females estimated by several vertical age-grading procedures ranged from 0.347 to 0.628. Both stage- and age-specific life tables were calculated from vertical age-grading data determined by the dilatation method. Female and male population size was estimated byBailey’s modification of theLincoln Index and was found to average 4478.4 and 6106.8, respectively. The bionomics, survivorship and population size ofAn. subpictus in the Lahore are indicated that this species was probably not important in the transmission of human malaria.     

The estimation of the fitness function from two samples taken from a population

Summary The fitness of animals subjected to natural selection can be defined as the probability of surviving selection for a given interval of time, or some convenient multiple of this probability. If the fitness of animals is related to some quantitative variableX (such as size) then this relationship is expressed mathematically in the fitness functionw(x) and this function can be estimated by comparing the distribution ofX in samples taken before and after selection. In this note five methods for estimating the fitness function on the basis of samples from a large population are discussed. They are compared on three previously published sets of data and as a result estimation according to weighted multiple regression is recommended.     

A further note on the estimation of a fitness function from two samples taken from a popolation

Summary A modification is proposed for the moments method for estimating a fitness function that was discussed in an earlier paper (Manly, 1976b). This modification ensures that fitness estimates are always positive. The theory has been worked out for a fitness function of any number of variables and a computer program has been written to carry out the iterative calculations needed for estimation.     

Midwives and sexual violence: A cross-sectional analysis of personal exposure,education and attitudes in practice

BackgroundAround one in three women experience sexual violence during their lifetime. They may need trauma-sensitive maternity care that takes sexual trauma triggers into account. Midwives are similarly likely to have experienced sexual violence in their lifetime. It is unknown whether midwives with a personal sexual violence history have a different professional approach to the topic than their colleagues without such history.AimTo explore whether midwives with a personal sexual violence history are more likely to have received or need education about sexual violence and whether they approach sexual violence differently in practice.MethodsAn exploratory online survey was conducted amongst practicing midwives in high resource countries. Odds ratios were calculated for differences between midwives with and without a personal sexual violence history.FindingsOf the 288 participating midwives, 48.6% disclosed a personal sexual violence history. Midwives with a personal sexual violence history showed higher uptake of post-graduate education (OR 2.05, 95% CI 1.23–3.44), more accurate prevalence estimation (OR 3.42, 95% CI 2.10–5.57) and more confidence to identify sexual violence history (OR 1.94, 95% CI 1.19–3.15). We found no differences in requiring future education, screening practices, other aspects of confidence or time and discomfort barriers.ConclusionsAs fellow survivors, midwives with a personal sexual violence history have a unique standpoint towards sexual violence in maternity care practice that may make them more sensitive to the issue.     

Problems in using birth-history analysis to estimate trends in fertility

Summary The problem investigated is the adequacy of birth-history analysis as a method for estimating fertility change. The analysis demonstrates that inaccurate reporting of the dates of birth of live-born children can, under reasonable assumptions, significantly distort cohort fertility schedules in such a way that estimates of change in fertility will be biased in the direction of exaggerating declines in fertility. This kind of bias is shown to exist in fertility estimates obtained from survey data in El Salvador and Bangladesh. An important implication is that birth history questionnaires should begin with the most recent, rather than the earliest, event in a respondent's experience.     

An empirical analysis of the welfare magnet debate using the NLSY

This paper examines the extent to which differences in welfare generosity across states leads to interstate migration. Using microdata from the National Longitudinal Survey of Youth (NLSY) between 1979 and 1992, we employ a quasi-experimental design that utilizes the categorical eligibility of the welfare system. The pattern of cross-state moves among poor single women with children, who are likely to be eligible for benefits is compared to the pattern among other poor households. We find little evidence indicating that welfare-induced migration is a widespread phenomenon. Received: 3 April 1997/Accepted: 4 September 1998     

Immigrant retention in NB: an analysis using administrative Medicare Registry data

Journal of Population Research - This paper examines immigrant retention using a novel approach based on data contained in New Brunswick’s Medicare Registry database. To date, researchers...     

Gay, lesbian, and bisexual content on television: a quantitative analysis across two seasons

Two annual content analyses of programming from the 2001-2002 and 2002-2003 television seasons (n = 1,276 and 1,439 programs, respectively) were conducted to assess the presence of behaviors and verbal messages related to the sexuality of gays, lesbians, and bisexuals. Sexual content associated with nonheterosexuals was found in about 15% of programs overall; however, rates of occurrence within episodes were low. Of 14 genres, only movies and variety/comedy shows had substantial percentages of programs that contained nonheterosexual content. Programs on commercial broadcast networks were less likely to have nonheterosexual content than those on cable networks, especially those on premium cable movie networks. Implications of the continued lack of attention to sexual minorities are discussed for both heterosexual and nonheterosexual viewers.     

Supplemental Security Income recipients affected by Hurricanes Katrina and Rita: an analysis of two years of administrative data

Approximately 350,000 Supplemental Security Income (SSI) recipients—elderly and disabled individuals with low incomes and assets—lived in the areas directly affected by Hurricanes Katrina and Rita in August 2005. We show that recipients from affected areas were more likely to leave the program, have more volatile participation patterns, and leave the area in the 2 years following the hurricanes than were recipients from unaffected areas. Among recipients from more severely affected areas relative to those from unaffected states, the odds of dying were 40% greater and the odds of leaving SSI for other reasons were 23% greater. Additionally, 31% of recipients from more severely affected areas had experienced a non-payment month, with 46% subsequently returning to the rolls (compared with 23% and 41% of recipients from unaffected states). Nearly 60% of SSI recipients from more severely affected areas lived in a different county or parish 2 years after the hurricanes, compared with about 12% from unaffected areas. In all, our findings demonstrate that natural disasters such as Hurricanes Katrina and Rita can have large and persistent impacts on SSI recipients, including effects on program status, mortality, and geographic location.     

Social inequality of reading literacy: A longitudinal analysis with cross-sectional data of PIRLS 2001 and PISA 2000 utilizing the pair wise matching procedure

In accordance to Boudon's structural-individualistic action model, it is the aim of this paper to investigate the casual effects of individual abilities, resources of the parental home, socially selective educational transitions as well as teaching and learning conditions in schools on the development of reading literacy and its dispersion in respect of social origin. It is assumed that the socially selective transition into the secondary school tracks contributes to the general deterioration of the mean reading literacy when controlling for social origin and individual achievement. The socially selective transition from primary to secondary school contributes to the increase of social inequality of reading literacy existing already since the start of the pupils’ schooling. Since it is not possible to isolate these causes with comparative-static cross-sectional data like PIRLS or PISA empirically, we use a design of generating quasi-longitudinal data with three time references, namely reading literacy at the point of enrolment into elementary school, at the age of 9–10 years, and at the age of 15 years by the pair wise matching of “synthetic twins” with identical status criteria. The empirical analysis of the German data of PISA 2000 and PIRLS 2001 confirm the effects of the individual abilities depending on social origin, the social selectivity of transition into the secondary schools, the sorting and selection performances of the school system, the allocation of children into different learning contexts, and the schooling of both the individual development of reading competences and the social inequality of reading literacy.     

Age patterns of mortality for older women: an analysis using the age-specific rate of mortality change with age

"In this paper we propose a mortality measure that seems useful in analyzing age patterns of death rates. The measure, which will be denoted by k(x), indicates the proportional increase or decrease with age in the risk of death at a given age x, and is called the age-specific rate of mortality change with age." Estimations are presented for women in 10 countries. "Eight of the selected sets of data are for developed nations in the 1960s and 1970s, and the other two sets of data, for Taiwan, 1931-35, and for Germany, 1910-11, represent relatively high mortality. For France and West Germany, three different periods are included for an investigation of cohort effects on the observed age patterns." Other mathematical models of age-specific mortality rates are discussed and compared. (SUMMARY IN FRE)     

Social networks, perceptions of risk, and changing attitudes towards HIV/AIDS: new evidence from a longitudinal study using fixed-effects analysis

The study presented here is an investigation of the importance of social interactions to perceptions of the risk of AIDS, and explores spousal communication about the AIDS epidemic in rural Malawi. A fixed-effects analysis based on longitudinal data collected in 1998 and 2001 shows that social interactions on the subject of HIV/AIDS have significant and substantial effects on respondents' perceptions of the risk of HIV/AIDS, even after controlling for unobserved factors that affect the selection of social networks. These effects are more complex than previously thought. The dominant mechanisms--social learning and social influence--are found to vary by sex and by region, because of regional variations in the marriage pattern and the resulting implications for the formation of local social networks. The conclusion of the study is that rather than fostering denial and inaction, social interactions are an important vector of change in the face of the HIV/AIDS epidemic.