Two methods are proposed to measure the effectiveness of a brand of sunscreen,
Which statement is a correct interpretation of these
methods?
Method A: Survey adults visiting a beach on a busy
weekend. Ask each adult which brand of sunscreen
they are using, and assess their arms for sun
exposure.
Method B: Volunteers are randomly assigned to
one of two brands of sunscreen. Each volunteer is
asked to report back at the end of the day, and their
arms are assessed for sun exposure.
O Both methods are experiments because sun
exposure is assessed in both methods.
Both methods are observational studies because
neither method attempts to influence responses.
O Method A is an experiment because it compares
many brands of sunscreen, while method B is an
observational study
O Method B is an experiment because it randomly
assigns volunteers a sunscreen, while method A is
an observational study.