Sampling Error / Margin of Error
The uncertainty inherent in estimating a population from a sample.
Short answer
What is Sampling Error / Margin of Error?
Sampling error is the range within which a sample-based estimate is expected to fall relative to the true population value, conventionally expressed as a margin of error at a stated confidence level.
Definition
Sampling error is the range within which a sample-based estimate is expected to fall relative to the true population value, conventionally expressed as a margin of error at a stated confidence level.
Why It Matters
A two-point lead in a survey with a four-point margin of error is not a lead. Campaigns that read survey point estimates as facts make confident decisions on noise.
Example in Indian Elections
Tracking waves are more informative than single surveys precisely because consistent directional movement across waves is meaningful even when any individual reading sits inside the margin of error.
Related Terms
- Vote ShareThe percentage of total valid votes polled that a candidate or party receives.
- SwingThe change in vote share between two elections, measuring movement of support.
- Stratified SamplingDividing a population into groups and sampling proportionately from each.
- Turnout PropensityThe modelled likelihood that a given voter will actually vote.
- Cross-TabulationBreaking survey results down by demographic or behavioural subgroups.
- Back-CheckRe-contacting a share of survey respondents to verify enumerator honesty.