What is a margin of error?

A margin of error is a statistical term that refers to the degree of accuracy of a poll or survey. It is typically expressed as a percentage and indicates the range within which the true population parameter (such as the percentage of individuals supporting a particular candidate) is likely to fall. A margin of error of 95% means that, based on the sample size and sampling methodology used, there is a 95% probability that the true population parameter falls within the margin of error.

For example, if a poll has a margin of error of +/- 3% at 95% certainty, it means that if the same poll were conducted multiple times, the results would fall within 3% of the true population parameter 95% of the time. In other words, if the poll found that 50% of respondents supported a particular candidate, the true population parameter (the percentage of the entire population that supports the candidate) is likely to be between 47% and 53% (a range of 3% on either side of the poll result).

It is important to note that the margin of error increases as the sample size decreases. This means that smaller sample sizes are less accurate than larger sample sizes, as there is a greater chance that the results will not accurately reflect the views of the entire population. In order to decrease the margin of error, pollsters will often use larger sample sizes or more sophisticated sampling methodologies.

Additionally, the margin of error is typically larger for subgroups within a population (such as specific age groups or geographic regions) due to the smaller sample size of these subgroups. This is why it is important for pollsters to accurately represent the demographics of the population being polled, in order to minimize the margin of error and increase the accuracy of the results.