Statistics - Statistic
1 - About
- in descriptive statistics, a descriptive statistic is used to describe the data;
- in estimation theory, an estimator is used to estimate a parameter of the distribution (population);
- in statistical hypothesis testing, a test statistic is used to test a hypothesis.
However, a single statistic can be used for multiple purposes – for example the sample mean can be used to describe a data set, to estimate the population mean, or to test a hypothesis.
A statistic is a descriptive number::
- any number that describes the individuals
- a numerical measure that describes a characteristic of a sample
A statistic, when used to estimate a population parameter, is called an estimator. For instance, the sample mean is a statistic that estimates the population mean, which is a parameter.
- a quantity calculated from a sample.
- Average Age of Students
A statistic describes a sample whereas a population parameter describes the population. A statistic is an observable random variable, which differentiates it both from a population parameter that is a generally unobservable quantity.
A statistic may not be representative for every individuals in the sample
The number of captured individuals is a statistic as it deals with the sample. The actual population is a parameter that we are trying to estimate.