Parameter and Statistics. Population and Sample.
Definitions
Parameter – a number calculated from the population. Usually denoted with a Greek letter. Often this number is a fixed, unknown number that you want to find.
Statistic – a number calculated from the sample. Usually denoted with letters from the Latin alphabet, though sometimes there is a Greek letter with a ^ (called a hat) above it. Since you can find samples, it is readily known, though it changes depending on the sample taken. It is used to estimate the parameter value.
Hint The alliteration in “population parameter” and “sample statistic” helps us remember the meaning of these terms.
If we are describing an entire population, we often will not be able to measure each person or thing in the population. We will usually measure a random sample from the population.
What are the two different meanings of the word “Statistics”?
1. a branch of mathematics dealing with the collection, analysis, interpretation, and presentation of data
2. plural of statistic: several quantities (such as the mean and variance of a sample) that are computed from a sample.
A sample statistics is usually
A population parameter is usually