Sample
A specific subset of individuals or entities selected from a larger population to participate in a research study.
What is Sample?
Because it is rarely feasible to study an entire population, researchers select a sample. The sample consists of the actual units of observation or participants from whom data will be collected. The validity of quantitative research heavily depends on how accurately the sample's characteristics reflect the broader population.
Why Sample Matters
The sample dictates the actual data available for analysis. If the sample is biased or unrepresentative, the statistical inferences drawn from it will be flawed, regardless of how sophisticated the analysis is.
Example
From a population of 10,000 registered university students, a researcher selects a sample of 500 students to complete a survey about campus dining options.
Common Mistakes
- Using a sample size that is statistically underpowered, leading to a high risk of Type II errors (failing to detect a real effect).
- Experiencing high dropout or non-response rates, transforming an initially representative sample into a biased one.