In this video we'll take a look at how to run a simple regression in SPSS. And
notice here in this example we have two variables, high school GPA and college
GPA. And we have the GPAs reported for 10 different people. So the first person,
for example, has a high school GPA of 3.10, and then when they went to college,
their college GPA was 3.45. The second person had a high school GPA of 2.15, and
their college GPA was 2.45, and so on. So we have 10 people with each person in a
different row and we have their GPAs on these two variables. Notice this looks a
lot like correlation, as we have two variables and each person produces a
score on each variable. And regression is really very similar to correlation and
in fact you'll see in the output some information about the correlation
between these two variables when we do our regression analysis. Now in simple
regression, we use the scores on one variable which we could call, generically,
X, to predict scores on some other variable which we can call generically,
Y. where here and regression, the X variable is called the predictor or the
independent variable and that's abbreviated by IV, and the Y is called
the criterion or the dependent variable, and that's abbreviated by DV. And simple
regression uses 1 X, or one independent variable, or predictor. Multiple
regression, if you're curious what that is, that's very similar to simple regression,
it just happens to use, not one X, but it uses two or more Xs, and that's the
key difference. Now there are some differences when we do the statistical
analyses, when we run the analysis in SPSS with multiple regression as compared to
simple regression, but the big picture, it just uses two or more independent
variables, where simple regression uses one independent variable.
So in this example, we're going to use high school GPA as our predictor, or
independent variable, that's going to be our X, and we're going to use that to
predict college GPA values. And this is very common, this is done in admission
offices in universities throughout the country. They will use variables like
high school GPA or high school rank, SAT scores, and so on, to predict college GPA,
where typically they predict the first year of GPA in college, which is what we can
assume this variable is, it's the first year of college GPA. So to run the
regression in SPSS, we want to go to Analyze, and then select Regression, and
then go down to the second choice here,
Linear. Notice the word linear, just like correlation, where we were measuring the
linear relationship between two variables, regression does the same thing,
in the sense that it requires there to be a linear relationship between the two
variables. Now there are differences between regression and correlation which you'll see
in just a minute, but they both require that there be a linear relationship
between the two variables. OK so we'll go ahead and click Linear. And then here the
Linear Regression dialog box opens.
Now notice the way it's represented here we have Dependent and Independent(s). And
recall here that our X is our predictor, or independent variable, Y is the
criterion or dependent. So this is Y and this is X. Recall that our X was high school
GPA, or our independent, and our dependent, or Y, was college GPA. In other words, we're
using high school GPA to predict college GPA. So we'll go ahead and move high
school GPA, our independent variable, to the Independent(s) box. We'll click on that,
move it to Independent(s). Then we'll select college GPA next and move that to
Dependent. Next we'll go ahead and click OK.