In a laboratory, smokers are asked to "drive" using a computerized driving simulator equipped with a stick shift and a gas pedal. The object is to maximize the distance covered by driving as fast as possible on a winding road while avoiding rear-end collisions. Some of the participants smoke a real cigarette immediately before climbing into the driver's seat. Others smoke a fake cigarette without nicotine. You are interested in comparing how many collisions the two groups have. In this study, the independent variable is . the use of nicotine the use of a driving simulator the number of collisions the number of accidents the driving skills of each driver

[120 total points] (public health) in one of the largest human experiments ever conducted, in 1954 a randomized controlled trial was run to see whether a vaccine developed by a doctor named jonas salk was effective in preventing paralytic polio. a total of 401,974 children (ages 6–9), chosen to be representative of those who might be susceptible to the disease, were randomized to two groups: 200,745 children (the control group c) were injected with a harmless saline solution (a placebo) and the other 201,229 children (the treatment group t) were injected with salk’s vaccine.what was the point of giving saline solution to the children who didn’t get the vaccine? explain briefly.

Which u.s. state is home to the fewest species of mosquitoes?

Me d: which system contains the heart, blood, and blood vessels? a. muscular b. circulatory c. respiratory d. digestive which system contains the pituitary, adrenal, and thyroid glands? a. respiratory b. circulatory c. endocrine d. reproductive