Title: What will reduce the width of a confidence interval?
Headings: What will reduce the width of a confidence interval?
Asked by: Yoandra Velikorechanin
What will reduce the width of a confidence interval?

Content: d) To reduce the width of a confidence interval by a factor of two (i.e., in half), you have to quadruple the sample size. True, as long as we're talking about a CI for a population percentage. The standard error for a population percentage has the square root of the sample size in the denominator. Secondly, what is considered a wide confidence interval? Intervals that are very wide (e.g. 0.50 to 1.10) indicate that we have little knowledge about the effect, and that further information is needed. A 95% confidence interval is often interpreted as indicating a range within which we can be 95% certain that the true effect lies. Besides, what 3 elements can influence the width of a confidence interval? The width of a confidence interval is affected by 3 measures: the value of the multiplier t* (which is driven by both the confidence level and the sample size), the standard deviation s of the original data, and the sample size n used for the data collection. Is a smaller confidence interval better?