Question

In: Statistics and Probability

Assume in Question 1 that the 90% confidence interval is .33<.42<.51. Interpret this interval. Explain why...

Assume in Question 1 that the 90% confidence interval is .33<.42<.51. Interpret this interval.

  1. Explain why a confidence interval should always accompany a point estimate.  
  2. Describe how changes in sample size change the size of confidence intervals?
  3. Describe how a 95% and an 85% confidence interval affects the width of the above 90% interval.

Solutions

Expert Solution

Assume in Question 1 that the 90% confidence interval is .33<.42<.51. Interpret this interval.

We are 90% confident that the population proportion will lies within the two points 0.33 and 0.51.

Explain why a confidence interval should always accompany a point estimate.  

A confidence interval should always accompany a point estimate, because the lower and upper limits are based on the point estimate and they are located same distance from the point estimate in opposite sides. A point estimate is a basis for the calculation of the confidence interval.

Describe how changes in sample size change the size of confidence intervals?

If we increases the sample size, the size or width of the confidence interval decreases. If we decrease the sample size, the size of the confidence interval increases.

Describe how a 95% and an 85% confidence interval affects the width of the above 90% interval.

The 95% confidence interval will increase the width of the above 90% interval, while 85% confidence interval will decrease the width of the above 90% interval.


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