Jennifer is doing a research
project on whether or not students in her school eat healthy food. She decides to interview her
friends who do gymnastics with her. Is her sample biased?
In order to work out if any
sample is biased, we need to ask ourselves one question. The question is this: does
every member of the population have an equal chance of being selected? In this question, the students
in Jennifer’s school are the population. She’s researching whether they
eat healthy food or not. In Jennifer’s sample, she’s
only selecting friends from gymnastics. This means that any students in
the school who do not do gymnastics cannot be selected.
The answer to the question
“Does every member of the population have an equal chance of being selected?” is
therefore no. If this is the case, we know
that the sample is biased or unfair. The correct overall answer is,
therefore, yes, Jennifer’s sample is biased. This is because the only
students that can be selected in her sample are those that do gymnastics. It is also quite possible —
although not certain — that many of the students who do gymnastics eat healthy
food. This means that the sample that
she has chosen could skew the results of her research project. They could potentially give a
more positive outlook on those students who eat healthy food.