Factors in the incidence of childlessness in Canada: An analysis of census data

The impact of the 1918 influenza pandemic on human fertility has been subject to significant scholarly debate. The current study characterizes the inter-temporal association between excess deaths during the pandemic and the subsequent birth deficit by identifying the length of time between these two phenomena using cross-correlations of monthly death and birth data from Taiwan from 1906 to 1943. The analysis demonstrates a strong and negative correlation between deaths (d) at time t and births (b) at time t + 9 (r_db(9) = –0.68, p < .0001). In other words, a significant drop in births was observed nine months after pandemic mortality peaked. The findings suggest that the 1918 influenza pandemic impacted subsequent births primarily through the mechanism of reduced conceptions and embryonic loss during the first month of pregnancy rather than through late-first-trimester embryonic loss.     

Socioeconomic status, marital status and childlessness in men and women: an analysis of census data from six countries

This study compares the effects of two distinct forms of human capital - income and education - on marital status and childlessness separately by sex in six different countries. Nearly 10 million individual records on individuals aged 16 to 50 were used from censuses from Brazil, Mexico, Panama, South Africa, USA and Venezuela dating from 2000 or later, to analyse the relationship between education, income and marital status and childlessness in men and women. Regarding income, the findings for both outcome variables are strongly consistent across all six countries. Highest-income males and lower-income females have the highest proportion of ever-married and the lowest proportion of childlessness (using a proxy for childlessness: own children in the household or not). There is no corresponding consistency of findings as regards education either between the sexes or among the countries. To conclude, a lower percentage of low-income men are selected by females, because for women male status and resources provided by men are important criteria in mate selection. Therefore a higher proportion of low-income men remain unmarried and childless. Thus selection seems to play a role in modern societies.     

Partial life cycle analysis: a model for pre-breeding census data

Matrix population models have become popular tools in research areas as diverse as population dynamics, life history theory, wildlife management, and conservation biology. Two classes of matrix models are commonly used for demographic analysis of age‐structured populations: age‐structured (Leslie) matrix models, which require age‐specific demographic data, and partial life cycle models, which can be parameterized with partial demographic data. Partial life cycle models are easier to parameterize because data needed to estimate parameters for these models are collected much more easily than those needed to estimate age‐specific demographic parameters. Partial life cycle models also allow evaluation of the sensitivity of population growth rate to changes in ages at first and last reproduction, which cannot be done with age‐structured models. Timing of censuses relative to the birth‐pulse is an important consideration in discrete‐time population models but most existing partial life cycle models do not address this issue, nor do they allow fractional values of variables such as ages at first and last reproduction. Here, we fully develop a partial life cycle model appropriate for situations in which demographic data are collected immediately before the birth‐pulse (pre‐breeding census). Our pre‐breeding census partial life cycle model can be fully parameterized with five variables (age at maturity, age at last reproduction, juvenile survival rate, adult survival rate, and fertility), and it has some important applications even when age‐specific demographic data are available (e.g., perturbation analysis involving ages at first and last reproduction). We have extended the model to allow non‐integer values of ages at first and last reproduction, derived formulae for sensitivity analyses, and presented methods for estimating parameters for our pre‐breeding census partial life cycle model. We applied the age‐structured Leslie matrix model and our pre‐breeding census partial life cycle model to demographic data for several species of mammals. Our results suggest that dynamical properties of the age‐structured model are generally retained in our partial life cycle model, and that our pre‐breeding census partial life cycle model is an excellent proxy for the age‐structured Leslie matrix model.     

Factors affecting the fruiting of bilberries: an analysis of categorical data set

The present study is an application of categorical data analysis in ecological research. The approach is based on logistic regression following an exploratory graphical analysis. The material was collected in an extensive forest inventory in which a set of observations was made by eye in a stratified random sample of 262 mature upland forest stands in South Finland. The problem was to interpret the variation in the fertility of the tillers of bilberry (Vaccinium myrtillus). In the field, the fertility was recorded as a three-class ordinal variable. The information available for the interpretation included the visually estimated density of the tree crowns, the soil fertility class determined using Cajander's forest site types and the percent cover of V. myrtillus.The GLM framework was employed in successive stages of the data analysis in order to find a model to fit the data. For this, the three-class ordinal response variable was reduced to two classes: stands characterized by (a) sterile and (b) fertile bilberry tillers. Successful prediction of the distribution of these two types of forest stands was achieved with a logistic-regression model by using canopy coverage and soil fertility classes as predictor variables. The generalized linear modelling framework is suitable for studying many ecological problems even when only rough categorical estimates of environmental scalars are available.     

Land use and cover with intensity of agriculture for Canada from satellite and census data

Aim To develop the first national databases on land use and agricultural land use intensity in Canada for a wide variety of environmental monitoring applications. Location Canada. Methods In this paper, we describe a new system for the construction of both land use and land use intensity (within agricultural regions) called LUCIA (land use and cover with intensity of agriculture). Our methodology combines the highly detailed Canadian Census of Agriculture and recent growing season composites derived from the SPOT4/VEGETATION sensor. Census data are of much coarser resolution than the remotely sensed data but, by removing non‐agricultural pixels from each census sampling area, we were able to refine the census data sufficiently to allow their use as ground truth data in some areas. The ‘refined’ census data were then used in the final step of an unsupervised classification of the remotely sensed data. Results and main conclusions The results of the land use classification are generally consistent with the input census data, indicating that the LUCIA output reflects actual land use trends as determined by national census information. Land use intensity, defined as the principal component of census variables that relate to agricultural inputs and outputs (e.g. chemical inputs, fertilizer inputs and manure outputs), is highest in the periphery of the great plains region of central Canada but is also very high in southern Ontario and Québec.     

Changes over time in means of suicide in Canada: an analysis of mortality data from 1981 to 2018

BACKGROUND:Ongoing surveillance of the means of suicide is necessary for effective prevention. We examined how mortality rates owing to different means of suicide changed in Canada from 1981 to 2018.METHODS:We obtained data from 1981 to 2018 on suicide deaths of individuals aged 10 years and older, from the Canadian Vital Statistics Death Database. We used joinpoint regression analysis to examine changes over time in the suicide mortality rate for the 3 most common means of suicide.RESULTS:The age-standardized suicide mortality rate declined in earlier decades for both sexes, but did not significantly change in recent decades for either sex. The age-standardized rate of suicide by suffocation increased from 1993 for females (2.1% per year) and from 1996 for males (0.4% per year). The age-standardized rate of suicide by poisoning decreased for females (2.2% per year) and males (2.1% per year) from 1981 to 2018. The age-standardized rate of suicide by firearm decreased from 1981 to 2008 (7.4% per year) but did not significantly change there-after for females; for males, it decreased 2.1% per year from 1981 to 1993 and 5.7% per year from 1993 to 2007, but did not significantly change thereafter.INTERPRETATION:For both sexes, the rate of suicide by poisoning is decreasing, the rate of suicide by suffocation is increasing, and the rate of suicide by firearm has not significantly changed in the last decade. Given the high proportion of suicide deaths by suffocation, its increasing rate and the difficulty of restricting the means of suffocation, other approaches to suicide prevention are needed.

The overall suicide mortality rate in Canada is lower than it was a few decades ago, but continued declines have been absent in recent years and the impact of suicide remains high.^1,2 Suicide was the ninth leading cause of death in 2018.³ More than three-quarters of suicide deaths in Canada are a result of suffocation, poisoning and firearms.^4–6 Suffocation is the predominant suicide method in most countries.⁴ However, the prevalence of different means of suicide can vary over time because of changes in the accessibility of certain means.⁷ Evidence suggests that the relative frequency of different means of suicide has changed in Canada, but those studies have not included data from more recent years.^8,9 Ongoing surveillance of the means of suicide and understanding changes over time are essential for designing and implementing prevention programs.¹⁰It is especially important to consider sex and age in suicide surveillance, because of differences across these sociodemographic characteristics. For instance, females are more likely to self-report thoughts of suicide and to be admitted to hospital owing to self-inflicted injuries,^5,11 while suicide mortality rates are about 3 times higher among males than females in Canada.^2,3,6 Higher suicide mortality rates for males have been observed in almost all countries,¹ and have been attributed, in part, to more lethal means of suicide (e.g., firearms).^5,6,12 Suicide-related behaviour also varies across the lifespan, with the suicide mortality rate tending to be high in middle-aged adults and males older than 80 years, but hospital admissions owing to self-inflicted injuries tending to occur during adolescence (particularly among females).^2,3,5,6,13Canadian data from 2000 to 2009 indicated that suicide by suffocation was more prevalent among individuals aged 15–39 years, while suicide by firearm was more prevalent among individuals aged 60 years and older.⁶ Canadian data for 2001 to 2011 suggested that rates of suicide by firearm and poisoning declined for males aged 15 years and older, but were unchanged among females during this period.⁹ Less is known about whether the means used by age and sex groups have fluctuated over longer periods and in more recent years. We sought to document the means of suicide deaths in Canada in 2018 (the most recent data available at the time of writing) and investigate how the use of different means has changed for males and females and across age groups since 1981.     

Sample size and the interpretation of census data

This article is directed toward the validity of sampling techniques. The adequacy of a 1/1000 sample is tested by comparing data based on it with similar data based on a proportionately larger sample. Mitra's 1966 data on the prevalence of childlessness among American women, based on a 1/1000 sampling of the 1960 U.S. census, was reformulated based on a sample 50 times larger. The reformulation is tabulated according to race and age of the women. Differences for white women over age 20 were not great; differences for smaller samples. e.g., nonwhites or women under 20, were substantial. Thus, the data was more reliable when the sampling base was very large; it was much less reliable when the sampling base was divided by 10.     

Deprivation payments to general practitioners: limitations of census data.

The census data from which deprivation payments have been calculated since June 1995 suffer from limitations including underenumeration; under counting of homeless people and refugees, and artefactual errors because of the way in which the 1991 census data were tabulated. These limitations reduced the fairness of the changes that many practices experienced in their deprivation payments. The validity of the current system of deprivation payments would be improved if these limitations were borne in mind when allocating payments to practices and if enumeration districts were used as the basis of payments rather than electoral wards.