To study the effects of noise on worker productivity, researchers have one group of subjects work in a noisy room and a second group work in a quiet room. to ensure that any differences in the productivity of the two groups actually result from the different noise levels to which the groups are exposed, the researchers would use

Which management function requires assigning tasks?

Which of the following is a nonspecific defense against pathogens? - b cells - antibodies - t-cells - inflammation

[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.