Measure content performance. Develop and improve products. List of Partners vendors. A population is a distinct group of individuals, whether that group comprises a nation or a group of people with a common characteristic. In statistics , a population is the pool of individuals from which a statistical sample is drawn for a study.
Thus, any selection of individuals grouped together by a common feature can be said to be a population. A sample is a statistically significant portion of a population, not an entire population.
For this reason, a statistical analysis of a sample must report the approximate standard deviation, or standard error, of its results from the entire population. Only an analysis of an entire population would have no standard error. In most uses, the word population implies a group of people or at least a group of living beings. However, statisticians refer to whatever group they are studying as a population. The population of a study might be babies born in North America in , the total number of tech startups in Asia since the year , the average height of all accounting examination candidates, or the mean weight of U.
Statisticians and researchers prefer to know the characteristics of every entity in a population in order to draw the most precise conclusions possible. This is impossible or impractical most of the time, however, since population sets tend to be quite large.
For example, if a company wanted to know whether most of its 50, customers were satisfied with the company's service last year, it would be impractical to call every client on the phone to conduct a survey. A sample of the population must be taken since the characteristics of every individual in a population cannot be measured due to constraints of time, resources, and accessibility. A population can be defined narrowly, such as the number of newborn babies in North America with brown eyes, the number of startups in Asia that failed in less than three years, the average height of all female accounting examination candidates, or the mean weight of all U.
The science of political polling offers a good example of the difficulty of selecting a random sampling of the population. One of the reasons why many of the last two presidential election polls have been wrong could be that the type of people who willingly answer poll questions may not constitute a random sample of the population of likely voters.
Nonetheless, surveys and polls may be the only efficient way to identify and validate issues and trends that affect the wider population. For example, growing concerns have been expressed about harassment online, but how common is it, really? A sample is a random selection of members of a population.
It is a smaller group drawn from the population that has the characteristics of the entire population. The observations and conclusions made against the sample data are attributed to the population as a whole. The information obtained from the statistical sample allows statisticians to develop hypotheses about the larger population. In statistical equations, population is usually denoted with an uppercase N while the sample is usually denoted with a lowercase n.
A parameter is data based on an entire population. Statistics such as averages and standard deviations , when taken from populations, are referred to as population parameters. A valid statistic may be drawn from either a population sample or a study of an entire population.
The objective of a random sample is to avoid bias in the results. A sample is random if every member of the whole population has an equal chance to be selected to participate. We can see that in , the age group with the highest share of the population was those aged , while in it was the age groups and From the shape of the pyramid, we can see that the population is getting older as the younger age groups are decreasing and the older ones increasing. This can also be illustrated by the median age of the population: in it was Back to Statistics 4 beginners - Introduction.
Tools What links here Special pages. Full article. How is the population in a country or given area calculated? Example In the EU on 1 January , the population was estimated at million compared with million on 1 January What other important indicators about the population are used? Some examples: The fertility rate is the average number of children born alive to a woman taking into consideration current fertility rates.
Example In , 5. Example Over the past 50 years, life expectancy at birth has increased by about 10 years for both men and women in the EU. Example In , some 4.
There are ways other than geography to define and study populations. Time , political leanings, religious beliefs or physical characteristics are all ways to divide people into different populations. The study of populations is accomplished by examining these different populations and seeing where they overlap. For example, if you know the population of Americans who are Republicans, and you know the population of Americans who live in Texas, you can study where those populations intersect and learn something about both Republicans and Texans.
Among the many reasons that we track population data, one is as important today as it was more than 1, years ago. What is that reason? Here's a hint -- the word census comes from the Latin word censere , which means "assess" [source: Bartleby ].
As in, assess taxes. The most basic though not necessarily easiest or most accurate way to measure population is simply to count everyone. This is known as a census and is usually undertaken by government officials. In the past, religious organizations carried out censuses, but usually on a local or regional level. The Roman Empire conducted censuses in order to measure the pool of military-age men and for taxation purposes, but these were limited because Romans had to report to government officials in their hometown to be counted.
The U. A full census is sometimes known as complete enumeration -- every single person is counted either through face-to-face interviews or through questionnaires. There are no estimates. Even a full census has limits. In countries with very remote areas, it can be impossible for census takers to count everyone. A census also has trouble collecting information on rare populations. A rare population is one that is small or not reflected in standard census data.
The United States isn't allowed to collect religious information in the national census, for example, so American Muslims could be considered a rare population.
People who participate in a particular hobby or own a certain model of car are other examples of rare populations. One alternative to a complete enumeration census is sampling. You might be familiar with this as the method used by market research companies and political analysts to conduct their research. Statisticians use a mathematical formula to determine the minimum number of people who must be counted to constitute a representative sample of the total population. For example, if the total population is 1, people, researchers might only need to survey of them directly.
Then they can take the data from the sample and extrapolate it to the full population. If 10 percent of the people in the sample are left-handed , it can be assumed that out of a population of 1, are left-handed. Sampling can actually return more accurate results than full enumeration, but there are some caveats. All samples have a margin of error , because there's always a chance that the sample selected for the survey differs from the total population in some way.
This is expressed as a percentage of possible variation, such as "plus or minus four percent. In addition, samples must be chosen as randomly as possible. This can be harder than it sounds. Let's say you want to survey a sample of everyone in France. One method used in the past was to select names at random from the phone book. However, this eliminates certain classes of people from the possibility of being selected for the sample: poor people with no phones; people who use cell phones and thus don't appear in the phone book; people with unlisted numbers; and most college students.
There may be partial censuses, local population data or information gathered by church or civic groups. Examining birth and death records provides other clues. All UN member nations conduct censuses and report the information to a central agency. The information is collected every 10 years, though it can take several years for all the nations to conduct their censuses [source: UN Statistics Division ]. Age - The age of a population can tell us a lot about what the population is doing, as well as what it will be doing in the future.
A larger than normal percentage of the population is then concentrated into a certain age group. As those people age, the bulge moves through the population and can have enormous societal effects. As Baby Boomers moved into middle age and started their own families, their tremendous purchasing power helped fuel the U. As they move into old age, they will exert immense pressure on the health care industry and Social Security. Location - Finding out where people live is one of the biggest reasons the United States conducts its census.
Legislators in the House of Representatives are allocated to each state based on that state's population. Many government programs base their funding on population patterns as well. Location data also tells us about the movement of people. Socio-economic data - Computer mapping software combined with population data can show us patterns that might provide clues to underlying problems. Such a map might show high concentrations of poor people in certain urban areas, or high concentrations of people with cancer near certain industrial sites.
Scientifically, there's no such thing as different "races" of human beings. If a high percentage of the population uses electricity legally, utility information can be used to estimate the vacancy rate. If multiple information sources are available, use an average of the two best vacancy rates. There are several ways to improve the information on building permits as well.
Verify whether the permits issued during the estimation period were actually used, and make sure they were used for housing units versus other types of construction, such as adding a room or garage to an existing house. Substitute certificates of occupancy for building permits if available.
These certificates are needed in order for new residents to move into a housing unit. Information on demolished buildings is often available from private companies that demolish buildings. In the example, information was not available on the number of housing units destroyed for each structure.
In this case, it is possible to improve the estimation, by identifying where buildings were destroyed and asking neighbors about the number of housing units that were in the buildings. Information on average household size was taken from the census. Household survey data could have been obtained from different studies to observe changes in household size and then averaged.
It is also possible to assess the quality of available census information. How did the census count the homeless? Did it collect information on those living in slum and squatter settlements? Try to determine how many people live in makeshift or temporary housing in squatter settlements. In most cases, makeshift housing appears overnight. If these types of housing units are not destroyed by government on a regular basis, include them in the count.
Also, check with institutions that provide services to the homeless to get an idea of how many to add to the estimation. These results can be compared with other estimates to see if they are too low or high see Lesson 6 for other tools that can be used to estimate the current population.
These are just a few examples of estimating. Experiment with different ideas to improve the accuracy of this tool in your locale. George W. Peter A. Norfleet W. Rives and William J. Henry S. Shryock and Jacob S. Health Information Systems. Maternal and Child Health. Introduction Course Objective Develop skills to estimate the population size of a given locale Expected Outcome Skills to estimate population size for two periods in time, the current year and a year between census periods.
An inter-census estimation is for a date between two census takings and usually takes the results of the two censuses into account. A post-census estimate is typically conducted for the current year.
Estimates involve the use of data that are based on the following information: Components of population change, including migration, fertility, and mortality Census results Information that reflects change in population size such as the number of housing units, postal or mailing addresses, registered voters, school enrollment, and users of metered water and other utilities.
This data can be divided into two categories: Direct information comes from census data and information on births, deaths, and migration. Filed under: Population.
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