The science of statistics involves collecting, analyzing, interpreting, and presenting data. The method of collecting, organizing, and summarizing data is called descriptive statistics. The systematic method of drawing inferences from the sample data and predicting unknown characteristics of a population is called inferential statistics.

In statistics, the collection of individuals or objects under study is called population. The idea of sampling is to select a portion of the larger population and study that portion (sample) to gain information about the population. Data are the result of sampling from a population.

Sampling is an efficient technique because it takes a lot of time and money to examine an entire population. For example, if the overall grade point average of all students in a school needs to be computed, it would make sense to select a few students and calculate their grade point average.

From the sample data, a statistic can be calculated. A statistic is a number that represents the property of the sample and gives an estimate of the population parameter. A parameter is a numerical characteristic of the whole population that a statistic can estimate. In the above example, the students from a particular class can be considered a sample of the entire school population. The grade point average of students in a single class is an example of a statistic. Since the students in the entire school were considered to be the population, then the average grade points earned per student in a class is an example of a parameter.

This text is adapted from Openstax, Introductory Statistics, Section 1.1 Definitions of Statistics, Probability, and Key Terms