QUESTION 6

Assume that we can use the Normal distribution to calculate a 80% Confidence Interval for the plaque index score for all 30 individuals in the study.

Using R Commander and PlaqueIndexScore2.csv, provide the lower value of the 80% confidence interval for mean plaque index score for all individuals in the study. Calculate your answer to TWO decimal places: X.XX and no other extraneous text.

QUESTION 7

Assume that we can use the Normal distribution to calculate a 80% Confidence Interval for the plaque index score for all 30 individuals in the study.

Using R Commander and PlaqueIndexScore2.csv, provide the upper value of the 80% confidence interval for mean plaque index score for all individuals in the study. Calculate your answer to TWO decimal places: X.XX and no other extraneous text.

QUESTION

For the plaque score data set, please choose the answer which best describes your interpretation of the 80% confidence interval for the mean plaque score calculated above?

a) There is a probability of 0.8 that the true sample mean is in the 80% confidence interval.

b) The confidence interval contains the true sample mean with a probability of 0.8.

c) The confidence interval contains the true population mean with a probability of 0.8.

d) There is a probability of 0.8 that the true population mean is in the 80% confidence interval.