Sample

From ForcaWiki, the simple encyclopedia

Imagine you want to know the average height of every kid in your entire school, but you do not have time to measure every single student. Instead, you measure just 30 kids, picked fairly from across every grade, and use their average height as your best guess for the whole school. Those 30 kids are your sample.

A sample is exactly that: a smaller group taken from a much bigger population, used in a research study when studying every single member of that population would take too long, cost too much, or simply be impossible. Researchers study the sample carefully, then use what they learn to make an educated guess about the entire, much larger group it was drawn from.

Why picking a good sample matters

A sample is only useful if it fairly represents the whole population. Measuring the height of only the tallest kids in school, for example, would give a very misleading guess about everyone else. Researchers work hard to choose samples fairly, often by picking people or things randomly, so that every member of the population has an equal chance of being included.

Fun facts

• Polls and surveys, like ones that try to predict an election, are built entirely on studying a sample of people rather than every single voter.
• A bigger sample usually gives a more trustworthy guess about the whole population, but even a well chosen small sample can be surprisingly accurate.
• The math behind Probability is what lets researchers say exactly how confident they can be that their sample's results reflect the truth about the whole population.