In the run-up to Election Day, polls attempted to predict the outcome of the 2020 election.

Many polls, though, came up short.

"The issue gets to be when we start looking at state-by-state polls," said Mark Murray, a professor of political science at South Texas College. "Some of them were fairly accurate and others were way off."

The sample size, method of contacting respondents and other factors contribute to the reliability of polls.

Another factor, the sampling error, which is also important to understand.

"The larger the sampling error, the less confidence the pollsters have in the respondents in percentages they receive from the respondents," Murray said. "So we'd like to see a sampling error as small as possible."

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