For findings to be valid, a sample must accurately reflect the characteristics of the whole population.

This occurs when the sample does not accurately represent the population, often due to poor selection methods. Common Sampling Techniques

The population is the entire collection of elements you want to study, while the sample is the specific group you actually collect data from.

Effective sampling relies on specific methodologies to ensure results can be generalized to the entire dataset. Data Collection | Definition, Methods & Examples - Scribbr

A is a representative subset of a larger dataset (the "population") used for analysis, modeling, or testing. This technique is essential for making analysis more manageable and cost-effective, as it avoids the need to process every individual data point in massive data sets. Core Concepts