Upper A study is conducted to determine if there is a relationship between brain cancer and
use of cell phones. Doctors ask patients with brain cancer about their use of cell phones.
Does the description correspond to an observational study or an experiment?
A.
The study is an observational study
because the study examines individuals in a sample comma
but does not try to influence the response variable.
B.
The study is an experiment because the study examines individuals in a sample, but does not try to influence the variable of interest.
C.
The study is an experiment
because the researchers control one variable to determine
the effect on the response variable.
D.
The study is an observational study because the researchers control one variable to determine the effect on the response variable.