Terms of Poll-i-tical Wisdom
- Bias
- A regular prejudice in one direction; in political polling, bias might result from polling only a certain economic or ethnic group, which could have unrepresentative opinions.
- Confidence interval
- An interval of results that is 95 percent likely to contain the true number; equals reported proportion plus or minus the margin of error. (For an alternative explanation).
- Hypothesis
- A supposition, or statement, used in science, that is precise enough to be tested.
- Margin of error
- A range of numbers used to determine the confidence interval, usually expressed as "plus or minus and x %". Note that the margin of error is computed on sample size and is only valid if the poll was well designed and executed on a true random sample. A poll with misleading questions will produce misleading results.
- Mean, or average
- The sum of a measurement, divided by the number of contributors to that measurement.
- n
- The sample size, generally the number of people questioned in a poll.
- p
- The probability that convincing results would occur due to chance alone; if p is less than .05 (often written "p < .05") the results are accepted as "statistically significant," or likely to be accurate at least 19 times out of 20.
- Population
- The larger group being studied. In political polls, the population is usually all eligible voters.
- Puny
- An amount so small it's hardly worth measuring (we think.)
- Random
- A way to choose a sample that represents all the people we want to reach (in political polling, that's usually likely voters). A sample is random if each member of the population has an equal chance of being represented.
- Reliability
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- Describes whether a measurement gives approximately the same result in repeated tests.
- Response rate
- The percentage of the originally identified sample that finally responds to the survey.
- Sample
- The number of people who were questioned.
- Sampling error
- An error derived from a mistake in sampling procedure.
- Standard deviation
- A statistical number that gauges how far any one measurement is likely to vary from the mean.
- Statistically significant
- A result which is at least 95 percent likely to be accurate; a result that would be produced by chance no more than 5 percent of the time.
- Systematic error
- An error or bias introduced by some methodological error.
- Tracking poll
- A poll conducted each day to assess trends caused by new advertising, public events, etc. Uses a relatively small sample; generally three to four days' worth of results are rolled together.
- Validity
- Validity gauges whether a statistic measures what it is supposed to measure.
- Volunteer error
- An error caused by the fact that some people had a chance to come forward with their opinions, and that biased the sampling.
