Female Life Tables Research Articles

Lifetime risk of pregnancy-related death among Zambian women: district-level estimates from the 2010 census

The aim of this study was to examine district differentials in the lifetime risk of pregnancy-related death among females aged 15–49 in Zambia. We used data on household deaths collected in the 2010 census to estimate the lifetime risk of pregnancy-related death among females in Zambia. Using all-cause age-specific death rates, we generated female life tables for 74 districts and estimated person-years of exposure to all-cause mortality at each age. We then applied age-specific pregnancy-related mortality rates to the person-years of exposure to obtain estimates of adult lifetime risk that took account of competing causes of death. We used the ArcGIS software to analyse clustering and the spatial distribution of risk. A female aged 15 in Zambia had a 3.7 % chance of dying a pregnancy-related death before the age of 50. At district level, the lifetime risk ranged from 1.7 to 7.7 %. The Global Moran’s I was 0.452 (z-score 5.8, p value <0.01), indicating clustering of districts with similar risk levels of pregnancy-related mortality. Clustering of high-risk districts was found in Western province while clustering of low risk districts was found in Lusaka and Muchinga provinces. The level of adult lifetime risk was more positively associated with pregnancy-related mortality than with fertility. Females in Zambia have a high lifetime risk of pregnancy-related death overall but this risk varies greatly across the different districts of the country. The observed diversity is larger than when merely studying differences between provinces and is only weakly linked to differences in fertility levels. The identification of districts with varying levels of risk should enable evidence-based and focused delivery of maternal health services in districts where risk of death from maternal causes is greatest.

연생모형을 이용한 역모기지의 분석

연생모형(multiple life model)은 보험계약에서 두 명 또는 그 이상의 피보험자들의 사망 또는 생존의 상태에 따른 보험금을 지급하는 보험 상품의 보험료 결정 및 리스크 관리를 위한 모형이다. 본 논문에서는 부부 가입자 중 마지막 사망자가 발생할 때까지 연금이 지급되는 연생보험의 대표적인 상품인 역모기지를 살펴보고자 한다. 역모기지 상품은 만 60세 이상의 고령자가 소유주택을 담보로 거주하면서 일정액을 대출받지만 대출금을 다시 상환하지 않는 금융상품으로 부부 가입의 경우 대출 기간의 확률분포를 적용하기 위해서는 연생모형을 적용해야만 한다. 그러나 현행 역모기지 상품에 있어서 대출한도 및 월지급금 산출 시 연생모형이 적용되지 않고 있으며 우리나라의 경우에는 국민 생명표 상의 여자 사망률을 대출 종료(연금지급종료)확률로 활용하고 있다. 여자의 사망률을 이용하는 이유는 보수적인 관점에서 대출 종료 시점을 예측하기 위해 일반적으로 남자보다 여자가 더 수명이 길다는 점 때문이다. 고령화로 인해 수명이 점점 길어지는 추세이기 때문에 역모기지와 같이 계약기간이 확정되어 있지 않은 보험 상품의 경우 특히 더 계약 종료 시점에 대한 확률분포가 리스크 관리를 위하여 중요하다. 본 논문의 의의는 역모기지의 발행기관 및 보증기관의 적정한 월지급금 지급과 차후 월지급금의 과대지급으로 인한 지급불능을 방지하기 위해 현행 사용하고 있는 모형의 위험률에서 연생 모형으로 변경할 필요성을 실증분석을 통하여 제시한다. Multiple life models are useful in multiple life insurance and multiple life annuities when the payment times of benets in these insurance products are contingent on the future life times of at least two people. A reverse mortgage is an annuity whose monthly payments terminate at the death time of the last survivor; however, actuaries have used female life table to calculate monthly payments of a reverse mortgage. This approach may overestimate monthly payments. This paper suggests a last-survivor life table rather than a female life table to avoid the overestimation of monthly payments. Next, this paper derives the distribution of the future life time of last survivor, and calculates the expected life times of male, female and last survivor. This paper calculates principal limits and monthly payments in cases of male life table, female life table and last-survivor life table, respectively. Some numerical examples are discussed.

Trends in scale and shape of survival curves.

The ageing of the population is an issue in wealthy countries worldwide because of increasing costs for health care and welfare. Survival curves taken from demographic life tables may help shed light on the hypotheses that humans are living longer and that human populations are growing older. We describe a methodology that enables us to obtain separate measurements of scale and shape variances in survival curves. Specifically, ‘living longer’ is associated with the scale variance of survival curves, whereas ‘growing older’ is associated with the shape variance. We show how the scale and shape of survival curves have changed over time during recent decades, based on period and cohort female life tables for selected wealthy countries. Our methodology will be useful for performing better tracking of ageing statistics and it is possible that this methodology can help identify the causes of current trends in human ageing.

Age‐stage, two‐sex life tables of Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) with a discussion on the problem of applying female age‐specific life tables to insect populations

Abstract Age‐stage, two‐sex life tables of the melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), reared on cucumber (Cucumis sativus L.), sponge gourd (Luffa cylindrica Roem) and a carrot medium (mashed Daucus carota L. mixed with sucrose and yeast hydrolysate) were constructed under laboratory conditions at 25 ± 1°C, 65%± 0.5% relative humidity, and a photoperiod 12 : 12 h (L : D). The intrinsic rates of increase of B. cucurbitae were 0.144 6, 0.141 2 and 0.068 8 days on cucumber, sponge gourd, and carrot medium, respectively. The highest net reproduction rate was 172 offspring per fly reared on sponge gourd. The mean generation times of B. cucurbitae ranged from 34 days reared on cucumber to 56 days reared on carrot medium. The life history raw data was analyzed using the traditional female age‐specific life table and compared to results obtained using the age‐stage, two‐sex life table. When the age‐specific female life table is applied to an age‐stage‐structured two‐sex population, survival and fecundity curves will be improperly manipulated due to an inability to include variation in preadult development time. We discussed different interpretations of the relationship between the net reproductive rate and the intrinsic rate of increase to clarify possible misunderstanding in the literature.

Life table and predation capacity of Hippodamia variegata (Coleoptera: Coccinellidae) feeding on Aphis fabae (Hemiptera: Aphididae)

The life history and predation rate of variegated lady beetle, Hippodamia variegata (Goeze), fed on the black bean aphid, Aphis fabae Scopoli, were studied under laboratory conditions. Developmental, survival, fecundity, and predation rate data were analyzed using the age-stage, two-sex life table and the traditional age-specific female life table. Means and standard errors of population growth parameters were calculated using the jackknife method. Using the age-stage, two-sex life table, the intrinsic rate of increase (r), net reproductive rate (R0), mean generation time (T) and finite rate of increase (λ) were 0.2031d−1, 389.0 offspring, 29.4d, and 1.2252d−1, respectively. The population parameters r, R0, T, and (λ) calculated using the female age-specific life table were 0.2045d−1, 387.6 offspring, 29.16d, and 1.2269d−1, respectively. Although no statistically significant differences were found between population parameters of the two methods, the female age-specific life table could not include the male population and its contribution to predation, nor was it possible to describe the stage differentiation. The net predation rate (C0) using the age-stage, two-sex life table was 1127.1 aphids, and 1503.1 aphids when using the female age-specific life table. The higher net predation obtained when using the female age-specific life table was an overestimation caused by ignoring the male population. Our results demonstrate that by using the age-stage, two-sex life table we can accurately describe the survival, development, and predation capacity of the predator.

MORTALITY TRANSITION IN INDIA 1970–2005

Using life tables, this paper analyses mortality transition in India from 1970 through 2005. The analysis reveals that the rise in the life expectancy in India has at best been slow by global standards despite the fact that mortality levels in India are still high. Improvements in the life expectancy has been particularly slow in the urban areas. The analysis also reveals that the rate of improvement in the probability of survival in the first five years of life has decelerated over time. For females, this probability has decreased in recent years. There has also been a considerable slowdown in the decrease in life table entropy, especially the female life table, indicating that the shift in the concentration of deaths towards older ages has slowed down. Hastening the pace of mortality transition in India requires a pragmatic, multi-dimensional approach, which is missing at present. There is a need to emphasize substantive health care rather than formal, institution-based care.

Update to Gage and O'Connor's “Nutrition and the Variation in Level and Age Patterns of Mortality” (1994)

It is widely assumed that nutrition influences the level of mortality. However, the association of nutrition and mortality is not linear; improved nutrition is associated with lower mortality when infectious causes of death dominate, but overnutrition, particularly with respect to the consumption of carbohydrates and fats, is often associated with increased chronic disease mortality. It is also possible that nutrition influences the age patterns of mortality. The age patterns of mortality are known to vary geographically among the world’s populations (Coale and Demeny 1966). Historically, these patterns tend to be geographically consistent even as the level of mortality declines. The cause of this human variation is under studied. Preston (1976) argued that the proximate causes of this variation result from varying geographic distributions of causes of death. Variation in nutrition may be responsible for some of this variation, possibly through influences on cause of death. The objective of our 1994 paper was to demonstrate the statistical association of the level of nutrition and dietary components on the overall level of mortality and the age patterns of mortality. For our 1994 paper we collected a worldwide sample of 341 life tables from 96 countries for the period 1952–1975 and matched them with standard national food balance sheet data for each country. One hundred seventyone tables were for males and 170 were for females; 1 female life table was excluded as defective. Expectation of life at birth in this sample ranged from 31.7 to 75.9 years. The independent variables included total calories and a principal components analysis of diet. In this case the components were interpretable as (1) a meat component, high in protein and fats, (2) carbohydrates, and (3) fats versus proteins. Standard regression analyses indicated that the international variation in nutrition was closely associated with the international variation in mortality. More than 50% of the variation was explained by these regressions, with respect to both level of mortality and the age patterns of mortality. The results indicated that total calories was positively related to expectation of life and was a better indicator than the percentage of caloric requirement. The analysis using dietary 1

Update to Gage and O'Connor's "Nutrition and the Variation in Level and Age Patterns of Mortality" (1994)

Update to Gage and O'Connor's "Nutrition and the Variation in Level and Age Patterns of Mortality" (1994) Timothy B. Gage and Kathleen O'Connor Keywords Nutrition, Mortality, Dietary Components, Age Patterns of Mortality. It is widely assumed that nutrition influences the level of mortality. However, the association of nutrition and mortality is not linear; improved nutrition is associated with lower mortality when infectious causes of death dominate, but overnutrition, particularly with respect to the consumption of carbohydrates and fats, is often associated with increased chronic disease mortality. It is also possible that nutrition influences the age patterns of mortality. The age patterns of mortality are known to vary geographically among the world's populations (Coale and Demeny 1966). Historically, these patterns tend to be geographically consistent even as the level of mortality declines. The cause of this human variation is understudied. Preston (1976) argued that the proximate causes of this variation result from varying geographic distributions of causes of death. Variation in nutrition may be responsible for some of this variation, possibly through influences on cause of death. The objective of our 1994 paper was to demonstrate the statistical association of the level of nutrition and dietary components on the overall level of mortality and the age patterns of mortality. For our 1994 paper we collected a worldwide sample of 341 life tables from 96 countries for the period 1952-1975 and matched them with standard national food balance sheet data for each country. One hundred seventy-one tables were for males and 170 were for females; 1 female life table was excluded as defective. Expectation of life at birth in this sample ranged from 31.7 to 75.9 years. The independent variables included total calories and a principal components analysis of diet. In this case the components were interpretable as (1) a meat component, high in protein and fats, (2) carbohydrates, and (3) fats versus proteins. Standard regression analyses indicated that the international variation in nutrition was closely associated with the international variation in mortality. More than 50% of the variation was explained by these regressions, with respect to both level of mortality and the age patterns of mortality. The results indicated that total calories was positively related to expectation of life and was a better indicator than the percentage of caloric requirement. The analysis using dietary [End Page 575] components was similar, except that higher carbohydrate levels were associated with increasing mortality and higher fat versus protein diets were associated with improved mortality, although this effect was attenuated at high and low levels because of significant interaction terms. An analysis of the impact of nutrition on the age patterns of mortality also indicated important associations. r2 values ranged from almost 90% to 20% depending on the parameter of the age patterns of mortality examined (age patterns were parameterized using the Siler model) and total calories versus dietary components. The age patterns of mortality appeared to be more closely associated with the dietary components than with simple calories. Overall, the results indicated that mortality improves as nutrition increases. No increase in mortality was observed even in the best (over?) nourished populations. Of course this might not be due to nutrition but to other phenomena correlated with nutrition, for example, modern medicine. The age patterns of mortality were closely associated with the nutrient composition of the diet, and the nutrients interacted in complex ways. Finally, the results indicated that the association of mortality (both level and age patterns) and nutrition was very strong, as indicated by the r2 levels. Despite the strong effects identified, our 1994 paper has generated few citations to date. Shaw et al. (2005) were unable to demonstrate the nonlinear association of dietary fats and mortality, although dietary fats was defined as "butter" in this study. On the other hand, Miller and Frech (2000) reported results similar to ours using data on all animal fats. Several reviews of diet quality indexes have also referenced the paper (Kant 1996; Seymour et al. 2003). However, the topic has a relatively small literature. Seymour et al. (2003) cited only ten other papers on this topic, only four of which clearly postdate the publication of our...

Epidemiological transition of mortality curves in terms of the Brass logit system.

"The purpose of this paper is to examine the long-term trends of life tables in developed countries according to two parameters of the Brass system in order to find the range of variation, consistent with historical life tables (or, in other words, to define 'a field of epidemiological transition')." The author finds that "1) In the past, the mortality curves had U- and J-shapes, the latter being connected with the impact of demographic crises....2) The elimination of the crisis component at the first stage of the transition resulted in the transformation of the mortality curves towards the U-shape....3) At the second stage social control is established over premature mortality. As a result, life expectancy grows, and the shape of the curves moves towards the J-shape....4) In the past the male and female life tables usually did not differ from each other as regards the value of the Brass model parameters. However, in the last 30-40 years considerable sexual differences emerged both in the level and in the shape of the mortality curves." (SUMMARY IN FRE)

Philopatry, Site Fidelity, Dispersal, and Survival of Spotted Sandpipers

We assessed philopatry, site fidelity, dispersal, and survival during the last eight years of an 18-year study of Spotted Sandpipers (Actitis macularia). The first 10 years of the study were of an island population. For the last eight years of the study, we expanded the study area to include a mainland subpopulation, 7 km from the primary island population. We also assessed between-site movement. Yearlings made up 7 to 36% of breeders recruited annually, and yearling return was negatively associated with number of fledglings the pre3;2;­ vious year. We found male-biased philopatry when all yearling returns were included, but no significant sex bias of birds that returned and bred. Return rate for males that successfully bred was 63%; for males that were not successful, 29% returned. For females, the return rate of successful breeders was 63% and for unsuccessful breeders 26%. Females changed territories between clutches more often after nest failure, and birds moved more often to the island than to the mainland. We used hatch and fledging success, philopatry, and site fidelity rates to construct male and female life tables, separating successful and unsuccessful breeders. From U.S. Fish and Wildlife Service recovery records, dispersal distances ranged from 3.6 to 147 km. We conclude that expanding our study site gave a more accurate picture of philopatry, dispersal, and site fidelity. Birds apparently treated all study areas as a single site, with the island preferred to the mainland for breeding.

Parity Progression and Birth Intervals in China: The Influence of Policy in Hastening Fertility Decline

Period parity progression ratios and interval distributions for China were estimated using parity specific birth probabilities and time since last birth a method used by Henry. The objective was to provide additional evidence of the role of and program efforts in contributing to Chinas fertility decline. Causation is inferred according to the timing magnitude and direction of fertility changes. Retrospective data were obtained from the National Fertility and Birth Control Survey in 1988 (2/1000 survey). Analysis was conducted on time series data on age at marriage and birth intervals at the national level for cities towns and counties and for the provinces of Jilin Shaanxi Jiansu and Guangdong. City refers to the urban unit excluding rural areas. The provinces reflected different levels of development and fertility patterns. The sample included women aged 15-57 years; since all Chinese women would have their first birth before age 35 there would be negligible age selection bias for first births in the years 1966-1987. Age selection bias for higher order births may be slightly affected in the earlier period but the year-to-year fluctuations would be unaffected. Older women underrepresented due to mortality were calculated using the female life table methods of Coale and Zhang and Lu; the effects were found to be quite modest. The findings show significant variation in mean age at first marriage which can be plausibly interpreted as a response to the government in the 1970s of the longer later fewer policy and in 1979 of the 1-child policy. There was an abrupt increase and a leveling off at 23 years of age which was the mean age required by for the period 1970-75. Relaxation of age at marriage restrictions and the introduction of the 1-child was reflected in the decrease to 22 years between 1979 and 1981 and stabilization through the 1980s. The use of the life table method for calculating the mean age at marriage provides an analysis without the influences of population by age and marital status. Separate analyses were conducted for marriage to first birth first to second second to third and fourth and high order births; and age at marriage in the four provinces. There was glaringly apparent evidence that the period parity progression ratios and mean birth intervals show the impact of the 2 policies on births which is roughly calculated at 60% attributed to and 40% to other factors.