Question

In: Statistics and Probability

Simulate 100 confidence intervals with a 90% confidence level. Choose a sample size between 30 and...

Simulate 100 confidence intervals with a 90% confidence level. Choose a sample size between 30 and 100. Look at your confidence intervals. Now increase the confidence level to 95%. Look at your confidence intervals. Finally, increase the confidence level to 99%. Look at your confidence intervals. How does the confidence level affect your confidence intervals?

Solutions

Expert Solution

Suppose, we simulate 100 confidence intervals with a 90% confidence level by using Excel or any other software with a specific sample size between 30 and 100. Suppose we select n=49. We simulate the confidence intervals based on the sample statistic values. Then again we did the same process by using a 95% confidence level instead of 90%. We have to do it again for the 99% confidence interval. After observing these simulated confidence intervals, it is observed that the width of the confidence intervals is increased when we increased the confidence level. The average width of the simulated confidence intervals with 95% level is more than the average width of the simulated confidence interval with 90% level. In the same way, the average width of the simulated confidence intervals with a 99% level is more than the average width of the simulated confidence interval with 95% level.

Example of simulated data is given for more explanation as below:

Example:

Sample Mean

10

10

10

Sample SD

2

2

2

Confidence level

90%

95%

99%

Sample size

49

49

49

df

48

48

48

Critical t value

1.6772

2.0106

2.6822

Standard error

0.2857

0.2857

0.2857

Margin of error

0.4792

0.5745

0.7663

Lower limit

9.5208

9.4255

9.2337

Upper limit

10.4792

10.5745

10.7663

Interval width

0.9584

1.1489

1.5327


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