A tire manufacturer is interested in testing the fuel economy for two different tread patterns. Tires of each tread type were driven for 1000 miles on each of 9 different cars. The mileages, in miles per gallon, were as follows: Car Tread A Tread B 1 24.6 20.0 2 22.3 19.0 3 24.0 22.7 4 27.1 22.9 5 22.2 20.5 6 23.3 23.4 7 22.9 21.7 8 19.6 17.8 9 27.5 26.0 Send data to Excel Part: 0 / 20 of 2 Parts Complete Part 1 of 2 (a) Construct a 99% confidence interval for the mean difference in fuel economy. Let d represent the mileage of tread pattern A minus the mileage of tread B. Use tables to find the critical value and round the answers to at least two decimal places. A 99% confident that the mean difference in fuel economy is

Aresearch study is studying the effects of a new drug for osteoporosis alzheimer's disease (ad) for women above the age of 65 years. a group of individuals with osteoporosis is randomized into two groups. one group is treated conventionally, and the second group is treated with the new medication. assessments are made at 3, 6, 12, 36, and 48 months. the conventionally treated group is assessed for ad using a serum blood test, and the treatment group is assessed for ad using a pet radiotracer that binds to beta-amyloid plaques. in comparing these 2 trial arms, the authors of the study may encounter which type of bias? a. selection bias on the risk of developing b. measurement bias c. confounding bias d. recall bias e. lead-time bias