Statistics Definition

Discrete Data

Can only take specific, separate values. Often involves counting.

Number of students in a class, number of pets owned

Continuous data:

Can take any value within a range. Often involves measurement.
Height, weight, temperature

Simple Random Sampling

In this method, each member of the population has an equal chance of being selected. It's often done using random number generators or tables.

To select 30 students from a school of 500, each student could be assigned a number from 1 to 500, and 30 numbers could be randomly drawn.

Convenience Sampling

This involves selecting readily available individuals or units for the study. While easy to implement, it often leads to bias.

Surveying only the people walking by a particular street corner on a Tuesday afternoon.

Systematic Sampling

This involves selecting every nth item from a population after a random start.
In a factory producing light bulbs, testing every 100th bulb coming off the production line.

Stratified Sampling

The population is divided into subgroups (strata) based on shared characteristics, and then samples are randomly selected from each stratum.

When studying student performance, dividing the school population into grade levels and then randomly selecting students from each grade.