Population > Interactive tools > Population clock > Method. explanations

Population clock – methodological explanations

Population clock for Slovenia

In Slovenia the data on the number and structure of population are published four times a year with a delay of four months. The population clock is an attempt to monitor the changes in the number of population on the basis of recent data on births, deaths and migration.

While more births occur in the summer months (July – October), more people die in winter (October - March). Migration is, however, largely dependent on economic factors.

World population clock

One can find many population clocks on the Internet. Understandably, data on them differ by several million. For example, the United Nations estimated that the “Day of 6 Billion” was 12 October 1999, while according to the U.S. Census Bureau it was 21 June 1999.

Basic data for the world population clock are taken over from the U.S. Census Bureau. They are based on analyses of available data on population, fertility, mortality and migration. The analysis is performed for 227 countries or areas of the world with a population of 5,000 or more. For most countries - especially less developed - adjustment of the data is necessary. Since the most recent data for each country are at least 2 years old, the population figures used for the clock are projections from those estimates based on assumed trends in fertility, mortality and migration. As new data become available, all data are corrected.