In this video I want to take a look at how to calculate the correlation
coefficient in Microsoft Excel when I have more than two variables. So in this
example I have SAT score, social support and this was recorded in college, and
then college GPA. So we have three variables and what I want to do is get
the correlation between all pairs of variables. So the correlation of SAT with
social support, the correlation of SAT with college GPA, and then the
correlation of social support with college GPA.
So to do that I want to go ahead and select Data and then Data Analysis and
then when this window opens up I want to go to Correlation and then click OK. Now
here I need to select the area of my variables and it's already selected here
but let's go ahead and redo that.
So start with the first label SAT score and scroll all the way down until we
have all the data selected. Notice that says B1 through D31 so those are all
the cells that are of interest. And then notice that I've gone ahead and selected
my labels which I wanted to do so I want to make sure I check this box Labels in
First Row and then notice it says Grouped by Columns and that's right each
variable is in a separate column so that looks great so let's go ahead and click
OK. And it opens up the results in a new worksheet. I'm going to go ahead and
expand these columns by double-clicking on them so we can see the information
better here and then I'll also go ahead and dial down these decimal places here
and we'll just take them to two decimal places.
OK now I'm going to highlight the correlation coefficients so they're
easier to see.
And then let's go ahead and
make this font a little larger as well so it's easier to see and I'll have to re-
expand just a bit more.
OK so these are our correlation results and notice here I have SAT Score, Social
Support, and College GPA and here where a column intersects with a row that
indicates the correlation. So the correlation .03 is the correlation or
relationship between the SAT score and social support and that's very small. And
then SAT correlates with college GPA .62 which is much higher that's a pretty
strong correlation. And then finally social support correlates with college
GPA .35. Now in this video what we're looking at when we're calculating the Pearson
correlation coefficient which is what this is. When we run this analysis in
Excel we get these correlation coefficients output it's important to
note here that all we're getting is the descriptive statistic or the correlation
between the two variables. But we haven't tested these for statistical
significance.
So while we know that the correlation here between college GPA and SAT scores
.62 we don't know for certain at this point whether that correlation is
significantly different from zero. It probably is just from experience here
but we don't know that by looking at this alone and we don't know for example
is .35 statistically significant this correlation between social support and
callege GPA. We can't tell that from this analysis. To know that we need to run
another procedure in Excel which I've done in another video which I'll link
to in this video for those who are interested. But it is important to be
aware of here
that running this procedure while definitely worthwhile it doesn't state
whether a given correlation is statistically significant or not.
So in other words we don't know whether this .35 is significantly different
from zero or no relationship. We need to establish that by conducting a
hypothesis test and unfortunately in Microsoft Excel it doesn't come out
automatically when you run
the correlation procedure but instead we need to run a different analysis.
OK that's it for running the Pearson correlation for multiple variables in
Microsoft Excel. Thanks for watching.