Question

identify the independent variable in the following investigation. scientists inject 50 people with an experimental vaccine immediately after exposure to ebola and 50 different people after a 21 day delay. the number of people who contract ebola are counted. a) the number of people who contract ebola b) the treatment with the experimental vaccine c) people not injected with the experimental vaccine d) the 21 day delay in the vaccinations

Explanation:

The independent variable is the one manipulated by the researcher. Here, scientists are manipulating the treatment (giving the experimental vaccine or not, with a delay). Option a is the dependent variable (outcome being measured). Option c is a control group, not the independent variable. Option d is a constant (21 - day delay is fixed). So the independent variable is the treatment with the experimental vaccine.

Answer:

b) the treatment with the experimental vaccine