Patrick Gerland
Biographic Data
| ID | 271146 |
|---|---|
| NAME | Patrick Gerland |
| GIVEN NAMES | Patrick |
| FAMILY NAME | Gerland |
| SIGNATURE | GERLAND P |
| AFFILIATIONS | United Nations Population Fund |
| ORCID | 0000-0002-2082-3122 |
| VERIFIED | Yes |
| TOTAL WORKS | 20 |
| TOTAL CITATIONS | 129 |
| AUTHOR COUNT | 20 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 2008 |
| LATEST PUBLICATION YEAR | 2026 |
| H-INDEX | 6 |
The Long‐Term Trends in Cohort Fertility
This study presents the first global dataset of fertility estimates and projections for cohorts of women born between 1935 and 2055. Leveraging the World Population Prospects 2024 revision, which provides single‐year single‐age fertility indicators for 1950–2100, we reconstructed cohort fertility profiles for all countries. These data offer a unique opportunity to analyze cohorts that have completed childbearing and those entering reproductive ag…
Modelling the age and sex profiles of net international migration
BACKGROUNDMany national statistical offices and international agencies use age and sex profiles of net migration as inputs into demographic accounting models for population estimation and projection.Commonly used residual methods for inferring these profiles have proven inadequate due to errors in the measures of populations, births, and deaths. OBJECTIVEWe test and apply a new methodology to infer the age and sex profiles of net international mi…
Global, regional, and national trends in under-5 mortality between 1990 and 2019 with scenario-based projections until 2030
BACKGROUND: The Sustainable Development Goals (SDGs), set in 2015 by the UN General Assembly, call for all countries to reach an under-5 mortality rate (U5MR) of at least as low as 25 deaths per 1000 livebirths and a neonatal mortality rate (NMR) of at least as low as 12 deaths per 1000 livebirths by 2030. We estimated levels and trends in under-5 mortality for 195 countries from 1990 to 2019, and conducted scenario-based projections of the U5MR …
Modeling Age Patterns of Under-5 Mortality
Information about how the risk of death varies with age within the 0–5 age range represents critical evidence for guiding health policy. This study proposes a new model for summarizing regularities about how under-5 mortality is distributed by detailed age. The model is based on a newly compiled database that contains under-5 mortality information by detailed age in countries with high-quality vital registration systems, covering a wide array of …
Projecting sex imbalances at birth at global, regional and national levels from 2021 to 2100
INTRODUCTION: Skewed levels of the sex ratio at birth (SRB) due to sex-selective abortions have been observed in several countries since the 1970s. They will lead to long-term sex imbalances in more than one-third of the world's population with yet unknown social and economic impacts on affected countries. Understanding the potential evolution of sex imbalances at birth is therefore essential for anticipating and planning for changing sex structu…
Systematic assessment of the sex ratio at birth for all countries and estimation of national imbalances and regional reference levels
Significance This study provides information on sex ratio at birth (SRB) reference levels and SRB imbalance. Using a comprehensive database and a Bayesian estimation model, we estimate that SRB reference levels are significantly different from the commonly assumed historical norm of 1.05 for most regions. We identify 12 countries with strong statistical evidence of SRB imbalance: Albania, Armenia, Azerbaijan, China, Georgia, Hong Kong (SAR of Chi…
Probabilistic projection of subnational total fertility rates
BACKGROUND: We consider the problem of probabilistic projection of the total fertility rate (TFR) for subnational regions. OBJECTIVE: We seek a method that is consistent with the UN's recently adopted Bayesian method for probabilistic TFR projections for all countries and works well for all countries. METHODS: We assess various possible methods using subnational TFR data for 47 countries. RESULTS: We find that the method that performs best in ter…
Patterns of Fertility Decline and the Impact of Alternative Scenarios of Future Fertility Change in sub‐Saharan Africa
Fertility decline in most countries of sub-Saharan Africa has thus far started later and proceeded more slowly than in countries in Asia and Latin America and the Caribbean undergoing the transition in fertility since the 1950s from high levels to near-replacement or even below-replacement levels (Bongaarts and Casterline 2013). Yet there is considerable variation among countries in sub-Saharan Africa: in the duration and magnitude of fertility d…
Bayesian population reconstruction of female populations for less developed and more developed countries
We show that Bayesian population reconstruction, a recent method for estimating past populations by age, works for data of widely varying quality. Bayesian reconstruction simultaneously estimates age-specific population counts, fertility rates, mortality rates, and net international migration flows from fragmentary data, while formally accounting for measurement error. As inputs, Bayesian reconstruction uses initial bias-reduced estimates of stan…
Global, regional, and national levels and trends in under-5 mortality between 1990 and 2015, with scenario-based projections to 2030
World population stabilization unlikely this century
The United Nations (UN) recently released population projections based on data until 2012 and a Bayesian probabilistic methodology. Analysis of these data reveals that, contrary to previous literature, the world population is unlikely to stop growing this century. There is an 80% probability that world population, now 7.2 billion people, will increase to between 9.6 billion and 12.3 billion in 2100. This uncertainty is much smaller than the range…
UN Population Division's Methodology in Preparing Base Population for Projections
Preparation of the base population plays a substantial role in the accuracy of projections. This paper reviews analytical strategies involved in the preparation of the UN World Population Prospects to reconcile existing discrepancies between data sources and derive robust estimates of population counts, distribution, and demographic changes. The case study of India is used to illustrate the challenges and benefits of using a cohort-component popu…
Joint probabilistic projection of female and male life expectancy
BACKGROUND: The United Nations (UN) produces population projections for all countries every two years. These are used by international organizations, governments, the private sector and researchers for policy planning, for monitoring development goals, as inputs to economic and environmental models, and for social and health research. The UN is considering producing fully probabilistic population projections, for which joint probabilistic project…
Bayesian Probabilistic Projections of Life Expectancy for All Countries
We propose a Bayesian hierarchical model for producing probabilistic forecasts of male period life expectancy at birth for all the countries of the world to 2100. Such forecasts would be an input to the production of probabilistic population projections for all countries, which is currently being considered by the United Nations. To evaluate the method, we conducted an out-of-sample cross-validation experiment, fitting the model to the data from …
Extending the Lee-Carter Method to Model the Rotation of Age Patterns of Mortality Decline for Long-Term Projections
In developed countries, mortality decline is decelerating at younger ages and accelerating at old ages, a phenomenon we call “rotation.” We expect that this rotation will also occur in developing countries as they attain high life expectancies. But the rotation is subtle and has proved difficult to handle in mortality models that include all age groups. Without taking it into account, however, long-term mortality projections will produce question…
Old age mortality in Eastern and South-Eastern Asia
Eastern and South-Eastern Asian countries have witnessed a marked decline in old age mortality in recent decades. Yet no studies have investigated the trends and patterns in old age mortality and cause-of-death in the region
Estimating trends in the total fertility rate with uncertainty using imperfect data
BACKGROUND: Estimating the total fertility rate is challenging for many developing countries because of limited data and varying data quality. A standardized, reproducible approach to produce estimates that include an uncertainty assessment is desired. METHODS: We develop a method to estimate and assess uncertainty in the total fertility rate over time, based on multiple imperfect observations from different data sources, including surveys and ce…
Aids Exceptionalism
Probabilistic Projections of the Total Fertility Rate for All Countries
We describe a Bayesian projection model to produce country-specific projections of the total fertility rate (TFR) for all countries. The model decomposes the evolution of TFR into three phases: pre-transition high fertility, the fertility transition, and post-transition low fertility. The model for the fertility decline builds on the United Nations Population Division’s current deterministic projection methodology, which assumes that fertility wi…
Hotspots and Coldspots
We explore the characteristics of households and villages in which orphans are resident in two areas of Malawi. We first review pertinent themes in qualitative data collected in our research sites. Then, using spatial analysis, we show how positive and negative clusters of orphans - which we term orphanhood "hotspots" and "coldspots" - can be found at the village and sub-village levels. In the third and longest section of the paper, and using mul…
Probabilistic Projections of the Total Fertility Rate for All Countries
We describe a Bayesian projection model to produce country-specific projections of the total fertility rate (TFR) for all countries. The model decomposes the evolution of TFR into three phases: pre-transition high fertility, the fertility transition, and post-transition low fertility. The model for the fertility decline builds on the United Nations Population Division’s current deterministic projection methodology, which assumes that fertility wi…
Bayesian Probabilistic Projections of Life Expectancy for All Countries
We propose a Bayesian hierarchical model for producing probabilistic forecasts of male period life expectancy at birth for all the countries of the world to 2100. Such forecasts would be an input to the production of probabilistic population projections for all countries, which is currently being considered by the United Nations. To evaluate the method, we conducted an out-of-sample cross-validation experiment, fitting the model to the data from …
Extending the Lee-Carter Method to Model the Rotation of Age Patterns of Mortality Decline for Long-Term Projections
In developed countries, mortality decline is decelerating at younger ages and accelerating at old ages, a phenomenon we call “rotation.” We expect that this rotation will also occur in developing countries as they attain high life expectancies. But the rotation is subtle and has proved difficult to handle in mortality models that include all age groups. Without taking it into account, however, long-term mortality projections will produce question…
Patterns of Fertility Decline and the Impact of Alternative Scenarios of Future Fertility Change in sub‐Saharan Africa
Fertility decline in most countries of sub-Saharan Africa has thus far started later and proceeded more slowly than in countries in Asia and Latin America and the Caribbean undergoing the transition in fertility since the 1950s from high levels to near-replacement or even below-replacement levels (Bongaarts and Casterline 2013). Yet there is considerable variation among countries in sub-Saharan Africa: in the duration and magnitude of fertility d…
Joint probabilistic projection of female and male life expectancy
BACKGROUND: The United Nations (UN) produces population projections for all countries every two years. These are used by international organizations, governments, the private sector and researchers for policy planning, for monitoring development goals, as inputs to economic and environmental models, and for social and health research. The UN is considering producing fully probabilistic population projections, for which joint probabilistic project…
Estimating trends in the total fertility rate with uncertainty using imperfect data
BACKGROUND: Estimating the total fertility rate is challenging for many developing countries because of limited data and varying data quality. A standardized, reproducible approach to produce estimates that include an uncertainty assessment is desired. METHODS: We develop a method to estimate and assess uncertainty in the total fertility rate over time, based on multiple imperfect observations from different data sources, including surveys and ce…
UN Population Division's Methodology in Preparing Base Population for Projections
Preparation of the base population plays a substantial role in the accuracy of projections. This paper reviews analytical strategies involved in the preparation of the UN World Population Prospects to reconcile existing discrepancies between data sources and derive robust estimates of population counts, distribution, and demographic changes. The case study of India is used to illustrate the challenges and benefits of using a cohort-component popu…
Hotspots and Coldspots
We explore the characteristics of households and villages in which orphans are resident in two areas of Malawi. We first review pertinent themes in qualitative data collected in our research sites. Then, using spatial analysis, we show how positive and negative clusters of orphans - which we term orphanhood "hotspots" and "coldspots" - can be found at the village and sub-village levels. In the third and longest section of the paper, and using mul…
Modeling Age Patterns of Under-5 Mortality
Information about how the risk of death varies with age within the 0–5 age range represents critical evidence for guiding health policy. This study proposes a new model for summarizing regularities about how under-5 mortality is distributed by detailed age. The model is based on a newly compiled database that contains under-5 mortality information by detailed age in countries with high-quality vital registration systems, covering a wide array of …
Probabilistic projection of subnational total fertility rates
BACKGROUND: We consider the problem of probabilistic projection of the total fertility rate (TFR) for subnational regions. OBJECTIVE: We seek a method that is consistent with the UN's recently adopted Bayesian method for probabilistic TFR projections for all countries and works well for all countries. METHODS: We assess various possible methods using subnational TFR data for 47 countries. RESULTS: We find that the method that performs best in ter…
Bayesian population reconstruction of female populations for less developed and more developed countries
We show that Bayesian population reconstruction, a recent method for estimating past populations by age, works for data of widely varying quality. Bayesian reconstruction simultaneously estimates age-specific population counts, fertility rates, mortality rates, and net international migration flows from fragmentary data, while formally accounting for measurement error. As inputs, Bayesian reconstruction uses initial bias-reduced estimates of stan…
Old age mortality in Eastern and South-Eastern Asia
Eastern and South-Eastern Asian countries have witnessed a marked decline in old age mortality in recent decades. Yet no studies have investigated the trends and patterns in old age mortality and cause-of-death in the region
Hotspots and Coldspots
We explore the characteristics of households and villages in which orphans are resident in two areas of Malawi. We first review pertinent themes in qualitative data collected in our research sites. Then, using spatial analysis, we show how positive and negative clusters of orphans - which we term orphanhood "hotspots" and "coldspots" - can be found at the village and sub-village levels. In the third and longest section of the paper, and using mul…
Aids Exceptionalism
Probabilistic Projections of the Total Fertility Rate for All Countries
We describe a Bayesian projection model to produce country-specific projections of the total fertility rate (TFR) for all countries. The model decomposes the evolution of TFR into three phases: pre-transition high fertility, the fertility transition, and post-transition low fertility. The model for the fertility decline builds on the United Nations Population Division’s current deterministic projection methodology, which assumes that fertility wi…
Estimating trends in the total fertility rate with uncertainty using imperfect data
BACKGROUND: Estimating the total fertility rate is challenging for many developing countries because of limited data and varying data quality. A standardized, reproducible approach to produce estimates that include an uncertainty assessment is desired. METHODS: We develop a method to estimate and assess uncertainty in the total fertility rate over time, based on multiple imperfect observations from different data sources, including surveys and ce…
Bayesian Probabilistic Projections of Life Expectancy for All Countries
We propose a Bayesian hierarchical model for producing probabilistic forecasts of male period life expectancy at birth for all the countries of the world to 2100. Such forecasts would be an input to the production of probabilistic population projections for all countries, which is currently being considered by the United Nations. To evaluate the method, we conducted an out-of-sample cross-validation experiment, fitting the model to the data from …
Extending the Lee-Carter Method to Model the Rotation of Age Patterns of Mortality Decline for Long-Term Projections
In developed countries, mortality decline is decelerating at younger ages and accelerating at old ages, a phenomenon we call “rotation.” We expect that this rotation will also occur in developing countries as they attain high life expectancies. But the rotation is subtle and has proved difficult to handle in mortality models that include all age groups. Without taking it into account, however, long-term mortality projections will produce question…
Old age mortality in Eastern and South-Eastern Asia
Eastern and South-Eastern Asian countries have witnessed a marked decline in old age mortality in recent decades. Yet no studies have investigated the trends and patterns in old age mortality and cause-of-death in the region
World population stabilization unlikely this century
The United Nations (UN) recently released population projections based on data until 2012 and a Bayesian probabilistic methodology. Analysis of these data reveals that, contrary to previous literature, the world population is unlikely to stop growing this century. There is an 80% probability that world population, now 7.2 billion people, will increase to between 9.6 billion and 12.3 billion in 2100. This uncertainty is much smaller than the range…
UN Population Division's Methodology in Preparing Base Population for Projections
Preparation of the base population plays a substantial role in the accuracy of projections. This paper reviews analytical strategies involved in the preparation of the UN World Population Prospects to reconcile existing discrepancies between data sources and derive robust estimates of population counts, distribution, and demographic changes. The case study of India is used to illustrate the challenges and benefits of using a cohort-component popu…
Joint probabilistic projection of female and male life expectancy
BACKGROUND: The United Nations (UN) produces population projections for all countries every two years. These are used by international organizations, governments, the private sector and researchers for policy planning, for monitoring development goals, as inputs to economic and environmental models, and for social and health research. The UN is considering producing fully probabilistic population projections, for which joint probabilistic project…
Global, regional, and national levels and trends in under-5 mortality between 1990 and 2015, with scenario-based projections to 2030
Patterns of Fertility Decline and the Impact of Alternative Scenarios of Future Fertility Change in sub‐Saharan Africa
Fertility decline in most countries of sub-Saharan Africa has thus far started later and proceeded more slowly than in countries in Asia and Latin America and the Caribbean undergoing the transition in fertility since the 1950s from high levels to near-replacement or even below-replacement levels (Bongaarts and Casterline 2013). Yet there is considerable variation among countries in sub-Saharan Africa: in the duration and magnitude of fertility d…
Bayesian population reconstruction of female populations for less developed and more developed countries
We show that Bayesian population reconstruction, a recent method for estimating past populations by age, works for data of widely varying quality. Bayesian reconstruction simultaneously estimates age-specific population counts, fertility rates, mortality rates, and net international migration flows from fragmentary data, while formally accounting for measurement error. As inputs, Bayesian reconstruction uses initial bias-reduced estimates of stan…
Probabilistic projection of subnational total fertility rates
BACKGROUND: We consider the problem of probabilistic projection of the total fertility rate (TFR) for subnational regions. OBJECTIVE: We seek a method that is consistent with the UN's recently adopted Bayesian method for probabilistic TFR projections for all countries and works well for all countries. METHODS: We assess various possible methods using subnational TFR data for 47 countries. RESULTS: We find that the method that performs best in ter…
Systematic assessment of the sex ratio at birth for all countries and estimation of national imbalances and regional reference levels
Significance This study provides information on sex ratio at birth (SRB) reference levels and SRB imbalance. Using a comprehensive database and a Bayesian estimation model, we estimate that SRB reference levels are significantly different from the commonly assumed historical norm of 1.05 for most regions. We identify 12 countries with strong statistical evidence of SRB imbalance: Albania, Armenia, Azerbaijan, China, Georgia, Hong Kong (SAR of Chi…
Projecting sex imbalances at birth at global, regional and national levels from 2021 to 2100
INTRODUCTION: Skewed levels of the sex ratio at birth (SRB) due to sex-selective abortions have been observed in several countries since the 1970s. They will lead to long-term sex imbalances in more than one-third of the world's population with yet unknown social and economic impacts on affected countries. Understanding the potential evolution of sex imbalances at birth is therefore essential for anticipating and planning for changing sex structu…
Global, regional, and national trends in under-5 mortality between 1990 and 2019 with scenario-based projections until 2030
BACKGROUND: The Sustainable Development Goals (SDGs), set in 2015 by the UN General Assembly, call for all countries to reach an under-5 mortality rate (U5MR) of at least as low as 25 deaths per 1000 livebirths and a neonatal mortality rate (NMR) of at least as low as 12 deaths per 1000 livebirths by 2030. We estimated levels and trends in under-5 mortality for 195 countries from 1990 to 2019, and conducted scenario-based projections of the U5MR …
Modeling Age Patterns of Under-5 Mortality
Information about how the risk of death varies with age within the 0–5 age range represents critical evidence for guiding health policy. This study proposes a new model for summarizing regularities about how under-5 mortality is distributed by detailed age. The model is based on a newly compiled database that contains under-5 mortality information by detailed age in countries with high-quality vital registration systems, covering a wide array of …
Modelling the age and sex profiles of net international migration
BACKGROUNDMany national statistical offices and international agencies use age and sex profiles of net migration as inputs into demographic accounting models for population estimation and projection.Commonly used residual methods for inferring these profiles have proven inadequate due to errors in the measures of populations, births, and deaths. OBJECTIVEWe test and apply a new methodology to infer the age and sex profiles of net international mi…
The Long‐Term Trends in Cohort Fertility
This study presents the first global dataset of fertility estimates and projections for cohorts of women born between 1935 and 2055. Leveraging the World Population Prospects 2024 revision, which provides single‐year single‐age fertility indicators for 1950–2100, we reconstructed cohort fertility profiles for all countries. These data offer a unique opportunity to analyze cohorts that have completed childbearing and those entering reproductive ag…
Demography (16 works) · Population (15 works) · Insurance, Mortality, Demography, Risk Management (14 works) · Sociology (13 works) · Geography (12 works) · Economics (11 works) · Global Maternal and Child Health (11 works) · Mathematics (10 works) · Econometrics (9 works) · Statistics (9 works)