2. Correlation is a way to measure how
associated or related two variables
are. The researcher looks at things
that already exist and determines if
and in what way those things are
related to each other.
4. In a positive correlation, as the values
of one of the variables increase, the
values of the second variable also
increase. Likewise, as the value of one
of the variables decreases, the value of
the other variable also decreases.
Positive correlation
5. Example:
There is a correlation between
income and education.
We find that people with
higher income have more
years of education.
6. Each point represents
one person’s answers to
questions about income
and education.
The line is the best fit to
those points.
7. As the values of one of the variables
increase, the values of the second variable
decrease. Likewise, as the value of one of the
variables decreases, the value of the other
variable increases.
Negative correlation
8. Example:
There is a negative correlation
between TV viewing
and class grades—students
who spend more time
watching TV tend to have
lower grades
9. On the scatterplot below, each point represents one person’s
answers to questions about TV viewing and class grades.
10. A correlation of zero means
there's no relationship
between the two variables.
As one variable moves one
way, the other moves in a
different, or unrelated,
direction
No Correlation
11. Finding the positive or negative
correlation between two variables is an
important way to study cause and
effect. By making these connections, we
can understand more about the world
around us — and we can use this
knowledge to make choices that affect
others as well.
