Suppose the z-score of your grade on this statistics exam turns out to be z=0.87. which of the following is the best interpretation of this z
-score?

i answered 87% of the questions correctly.

a. my grade is the 87th percentile.
b. my grade is 0.87 points above the mean.
c. my grade is 0.87 standard deviations above the mean.

Researchers are conducting experiments to determine the role of alcohol in the development of depression. after the study is complete, they determine that the relative risk of developing depression is 1.55 with a 95 % ci of 1.2 -1.9. each group is then divided into nonsmokers and smokers. the relative risk for the nonsmokers is 1.12 with a 95% ci of 0.87-1.37. the relative risk for the smokers is 1.7 with a 95 % cl of 1.5-1.9. what type of bias may affect this study? a. procedure bias b. recall bias c. selection bias d. confounding e. lead-time bias