On Tuesday, April 15th, 2014 Gallup reported that 43% of Americans approve of the job Barack Obama is doing as president. This proportion is based on phone surveys with approximately 1500 American adults.
By hand, compute a 95% confidence interval for the proportion of all American adults who approve of the job Barack Obama is doing as president. zc for a 95% confidence interval is 1.96.
By hand, compute and interpret a 99% confidence interval for the proportion of all American adults who approve of the job Barack Obama is doing as president. zc for a 99% confidence interval is 2.58.
What is happening to the range of the confidence intervals for presidential approval rating as the confidence level increases? Explain why this is happening.