Title: Confidence Level: What is it? - Statistics How To
Headings: Confidence Level: What is it?
Confidence Level: What is it?
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Real Life Example
What about “+/- 3 percentage points”?
Factors that Affect Confidence Intervals (CI)
0% and 100% Confidence Level
Confidence Coefficient
References

Content: What a 95 percent confidence level is saying is that if the poll or survey were repeated over and over again, the results would match the results from the actual population 95 percent of the time. What about “+/- 3 percentage points”? The width of the confidence interval tells us more about how certain (or uncertain) we are about the true figure in the population. This width is stated as a plus or minus (in this case,+/- 3) and is called the confidence interval. When the interval and confidence level are put together, you get a spread of percentage. In this case, you would expect the results to be 35 (38-3) to 41 (35+3) percent, 95% of the time. Factors that Affect Confidence Intervals (CI)
Population size: this does not usually affect the CI but can be a factor if you are working with small and known groups of people. Sample Size: the smaller your sample, the less likely it is you can be confident the results reflect the true population parameter.