Question

Before elections polling companies survey voters. They want to estimate the proportion of voters who plan to vote for each candidate . As the election gets closer polling companies often use larger sample sizes in their surveys. Why they do this? Alarger size gives more voters the opportunity to give their opinion A sample site help fix poor sampling methods. With a larger sample size the polling company can be certain that their sample results exactly match the population Alarger sample size gives more precise results with a smaller margin of error

Answer 1

The polling companies increase the sample size of population as the election gets closer because for the result to be predicted correctly they would have to interview everyone in the population but that's not possible so they take a bigger sample size of the population to reduce the margin of error.

Suppose we have a margin of error of plus or minus 5% at 78 % of confidence level means that if we field the same survey 100 times the result will be within 5% of the true population value 78 of those Times.

Show the sample size is increased to reduce the margin of error in order to predict the results correctly as close as possible to the true result.