7 billion people and you: FAQs

7 billion graphic

The BBC News website's guide, 7 billion people and you: What's your number?, which attempted to explain how each individual fitted into the history of human life on earth, has been enormously popular.

As a result, we have received hundreds of emails asking a range of questions. Here are the answers to some of the most popular.

Where did you get the information from?

The data is provided by the Population Division of the Department of Economic and Social Affairs at the United Nations, which prepares demographic estimates and projections for all countries and areas of the world. Their data serves as a consistent set of global population figures and may differ from your country's own figures.

The latest data is found in the UN Population Division's 2010 Revision of the World Population Prospects, released on 3 May 2011. The division issues a new revision every two years. The next one is due in the first half of 2013.

You can explore and download more detailed figures through the UN's data website.

How did you calculate people's individual numbers?

The numbers were calculated by the UN Population Fund, another section of the UN which helps countries use population data to aid development.

It was calculated using an algorithm, or mathematical formula, based on historical population data and growth rates over time.

The second number also includes calculations based on the methodology of scholar Carl Haub, who estimated how many people had been alive since 50,000 B.C. His calculation has been amended by the UN to include additional points in time.

The UN Population Fund has its own more detailed calculator, 7 billion and me, which you can also try. However, some of the numbers may be slightly different to those in the BBC guide because of the way the BBC's application was configured by developers.

Why isn't my country included?

Some island nations and smaller countries are not included because comprehensive and comparable data was only available for those with populations over 100,000.

Where is the information on Kashmir?

The information in the guide is that available through the UN Population Division. In the UN's data all territory under Indian control is included in India's data and all territory under Pakistan's control is under Pakistan. For this reason, Kashmir features in both countries' data.

Why doesn't it show emigration as well as immigration?

We have shown just one figure for net immigration for each country for simplicity. Some countries will show a positive number and some a negative number.

Why is Qatar shown as the fastest-growing nation when my country increases by more people per year?

Qatar has the fastest rate of annual growth in relation to the size of its population. However, in the application we chose to show the increase in people per day rather than a percentage change because we thought users would find that number easier to understand. So, even though many countries will increase by more people per day than Qatar, in relation to the total size of its population Qatar is the fastest growing.

Does the BBC store people's results?

No. The application does not store users' details or send them over the internet. All the information the user puts into each field stays on their machine. However, users do have the option to share their number on Facebook or Twitter.

This application does not use cookies, so when a user returns to the guide, they will not see their previous results - they will have to input them again.

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