Consider the following expression and determine which statements are true.
2gh-(3+7)+x/4
A The term X/4 is a quotient of two variables
B The expression 2gh-(3+7) is a difference
C Nicole efficiency of the expression are 2 and 1/4
D The expression 3+7 is a sum

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