Population and sample

In statistics, the term ‘population’ has a much wider meaning than in everyday language. The complete set of people or things that is of interest to you in its own right (and not because the collection may be representative of something larger) is a population. The number of items, known as cases, in such a collection is its size. For example, if you are interested in all the passengers on a particular plane in their own right and not as representatives of the passengers using the airline which owns that particular plane, then those particular plane passengers are your population.

But if you do a statistical analysis of those particular plane passengers in order to reach some conclusion about, say, (1) all plane passengers heading to that destination, or (2) all plane passengers on any route on that day and at that time, then the passengers are a sample. They are being used to indicate something about the population (1) or (2). A sample is therefore a smaller group of people or things selected from the complete set (the population). It hardly goes without saying that you need to be clear about whether your data are your population or a sample. Most of statistics concerns using sample data to make statements about the population from which the sample comes.

5. Write out the definitions out of the texts:

Cardinal numbers; ordinal numbers;

population; sample.

6. Complete the following sentences:

· ‘Cardinal’ in statistics is not a person ….

· Cardinal numbers are 1, 2, 3 and so on, and …..

· An ordinalnumber describes ….

· They express order or ranking, and …..

· Most of the statistical techniques created for the analysis of quantitative …

· In statistics, the term ‘population’ has a much …

· The complete set of people or things that is of interest to …

· A sampleis therefore a smaller group of people or ….

· You need to be clear about whether your data are ….

· Most of statistics concerns using sample data to make ….