Transcript 1.3 Power Point

Sections 3
Introduction to
Experimental
Design
Definitions
treatment – the property being
studied
treatment group – the group
possessing the property
control group – the group not
possessing the property
Definitions continued
confounding factors – properties
other than the treatment that can
influence a study
observational study
the researcher does not control
which subjects are assigned to the
treatment
observations and measurements of
individuals are conducted in a way
that doesn’t change the variable
being measured
controlled experiment
the researcher can control which
subjects are assigned to the
treatment
a treatment is deliberately imposed
on individuals in order to observe a
possible change in the variable being
measured
Types of studies
cross-sectional
study - different
subjects are
compared to one
another at the
same point in time
longitudinal study the same subjects
are compared to
themselves at
different points in
time
A researcher is attempting to
measure the effectiveness of a
new drug that claims to lessen
the severity of heart attacks.
Half of the study participants are
given the drug and the
remainder are given a placebo.
1.) Does the study depict a controlled
experiment or an observational
study?
2.) What is the treatment?
3.) What is the treatment group?
4.) What is the control group?
5.) Name a confounding factor that
could influence the study.
Determine whether the study depicts an
observational study or a controlled experiment.
1. A study to determine whether there is a
relationship between the rate of cancer
and an individual’s proximity to hightension wires.
2. Rats with cancer are divided into two
groups. One group receives 5 mg of an
experimental drug that is thought to fight
cancer, and the other receives 10 mg.
After two years, the spread of cancer is
measured.
Determine whether the study depicts an
observational study or a controlled experiment.
3. While shopping, 200 people are
asked toperform a taste test in which
they drink from two unmarked cups.
They are then asked which drink
they prefer.
4. A survey is conducted asking 400
people, “Do you prefer Coke or
Pepsi?”