To test a new drug that has the potential of curing people of the common
cold, a company asked human volunteers who were coughing and sneezing
to participate in a clinical study. the objective of the experiment was to test
whether the new drug could cure the volunteers in the experimental group of
the common cold. but instead of two groups, these volunteers were randomly
divided into three groups and treated as follows:
group
control
group #1
experimental
group
yes
yes |
no
new drug
orange juice
bed rest
control
group #2
no
no
yes
yes
yes
yes
which of the following is the best explanation of why a second control group
was included in this experiment?