Planet Litmess has a cellular service plan with unlimited minutes for $25 per month and messaging for $0.20 per message. Phones for Less has a service plan with unlimited minutes for $55 per month and messaging for $0.50 per message. What number of messages costs the same at both companies? X = # of messages Y = cost
Planet Litmess: y = 25 + 0.2x
Phones for Less: y = 55 + 0.5x

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