Sample

Last updated Jun 5, 2023

A part of a Population that is representative of the population.

Refs:

• Sampling bias

Minimum 30.

This recommendation is based on the Central Limit Theorem (CLT) in the field of probability and statistics. As sample size increases, the results more closely resemble the normal (bell-shaped) distribution from a large number of samples. A sample of 30 is the smallest sample size for which the CLT is still valid. Researchers who rely on regression analysis – statistical methods to determine the relationships between controlled and dependent variables – also prefer a minimum sample of 30.

Still curious? Without getting too much into the math, check out these articles:

• Central Limit Theorem (CLT): This article by Investopedia explains the Central Limit Theorem and briefly describes how it can apply to an analysis of a stock index.

• Sample Size Formula: This article by Statistics Solutions provides a little more detail about why some researchers use 30 as a minimum sample size.

Link: https://docs.google.com/spreadsheets/d/1kBTvnpH2qOLJx4XWjUG1v-GF4LPmOhequy_9VRyslJ8/template/preview