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Featured image for article on Global Terrorism Database. Stylized line chart indicating the number of terrorist attacks, deaths, and non-fatal injuries over time.

The Global Terrorism Database: how do researchers measure terrorism?

There are different approaches to measuring terrorism. Here is the approach of the Global Terrorism Database, a leading source of terrorism data.

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How do researchers estimate the death toll caused by each risk factor, whether it’s smoking, obesity, or air pollution?

Risk factors are important to understand because they can help us identify how to save lives. How do researchers estimate their impact?

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Thumbnail for the article How are causes of death registered around the world?

How are causes of death registered around the world?

In many countries, when people die, the cause of their death is officially registered in their country’s national system. How is this determined?

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Risk ratios, odds ratios, risk differences: How do researchers calculate the risk from a risk factor?

The effects of risk factors can be calculated in different ways. How are they calculated and interpreted?

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A thumbnail image for the article How do researchers estimate the death toll from risk factors

Why isn’t it possible to sum up the death toll from different risk factors?

Deaths caused by each risk factor can’t be added up. By understanding why, we will have a better understanding of how many lives can be saved with each intervention.

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The limits of our personal experience and the value of statistics

The world is huge; to get a clear idea of what our world is like, we have to rely on carefully collected, well-documented statistics.

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Sustainable development goal Tracker

SDG Tracker: Measuring progress towards the Sustainable Development Goals

Our World in Data’s Sustainable Development Goals Tracker

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Consumer Price Index over time, converging to base year

How are incomes adjusted for inflation?

Adjusting incomes for inflation is crucial if we want to learn how standards of living are changing. How is this adjustment done?

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U-shaped inequality trends over past century

How has income inequality within countries evolved over the past century?

While the steep rise of inequality in the United States is well-known, long-run data on the incomes of the richest shows countries have followed a variety of trajectories.

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Incomes by decile

OWID Data Collection: Inequality and Poverty

Explore a wide range of indicators on inequality and poverty and compare sources.

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Scatter chart, before and after tax income inequality

Income inequality before and after taxes: how much do countries redistribute income?

The redistribution of income achieved by governments through taxes and benefits varies hugely.

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Measuring inequality: what is the Gini coefficient?

The Gini coefficient is the most common way of measuring inequality. But what does it actually measure? And how does it differ from other measures of inequality?

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Featured image for the article on the different homicide data sources. Stylized lines that all go down.

Homicide data: how sources differ and when to use which one

There are several ways to measure homicides. What approaches do different sources take? And when is which approach best?

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Population momentum: if the number of children per woman is falling, why is the population still increasing?

50 years ago, the total fertility rate was five. This figure has more than halved. Yet the global population is still rising — why?

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How do researchers study the prevalence of mental illnesses?

Global data on mental health is essential to understand the scale and patterns of these illnesses, and how to reduce them. How do researchers collect this data, and how reliable is it?

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How are mental illnesses defined?

Mental illnesses are a range of conditions that significantly affect people’s lives. What are their symptoms?

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How is food insecurity measured?

Billions of people suffer from food insecurity. What does it mean to be food insecure?

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Learning curves: What does it mean for a technology to follow Wright’s Law?

Technologies that follow Wright’s Law get cheaper at a consistent rate, as the cumulative production of that technology increases.

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Mortality in the past: every second child died

The chances that a newborn survives childhood have increased from 50% to 96% globally. How do we know about the mortality of children in the past? And what can we learn from it for our future?

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A line graph featuring three distinct lines plotted on a light gray background.

How does age standardization make health metrics comparable?

Age standardization is a statistical method used to compare disease rates, or other health indicators, between populations while accounting for differences in their age structure.

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Artificial intelligence has advanced despite having few resources dedicated to its development — now investments have increased substantially

The available resources have increased substantially. We should expect that the field continues to advance rapidly.