Computing a new variable in SPSS

So here we are in SPSS

I have created kind of a junk data set

just to help illustrate how we can compute

variables or compute new variables

using the variables form existing ones.

This is a pretty straight forward process,

it looks a little bit different

than things that we've done before

or other ways that we are going

to be using an SPSS in this course.

So it might look a little bit different,

but it is pretty straight forward

and pretty easy

once you know how to do this.

So the first that we'll do

is to go to Transform and then

the first option we have there

is Compute Variable. So click on that.

We get this new window that pops up

The first that we really want to look at

is in the top left and that's this target

variable window.

Basically what the computer

is asking you

is to create a name for the new variable

that you are going to be computing.

This name needs to be unique,

it's one that can't have spaces in it

and it should avoid special characters.

In this case, what I like

to do is include some sort of piece

of information in the naming convention

I use that helps me know what this is

just by looking at it.

So what we're going to be doing

is we are going to be summing items

one, two, three, four, five, six together,

adding those together.

So an easy way to do that,

is just to put sum of items.

That way when I look at this new variable

once it's generated

I know that that's the variable

that I really want to be working with.

Or running my tests on because that

that contains the information

from the other ones. You can

click on type and label. The label is the

more drawn out explanation,

that's the one you can include character

additional characters or spaces

and special characters. In that case,

I'm going to put this is the sum of items

one through six.

And that way, I know that that is going to

give me more drawn out explanation of what

this variable includes. We know this is

going to be uneric - numeric - I'm sorry,

so click Continue. The next thing

we are going to look at is this

numeric expression box - we're going

to come back to this in just a minute.

But this is where you're going to be doing

most of the work when you're computing

variable. What you want to go to next

is this function group area.

So I'm going to click on All

and you notice right below it

we've got these functions and special variables

and this pop up when I clicked on all.

This has a whole bunch

of pre-existing functions, so you

don't need to reinvent the wheel.

You can basically use these

pre-existing functions to help you

compute this new variable.

Um, I'm going to go down

to Sum and these are in alphabetical order

so it's pretty easy to find.

Here we have Sum and when I click on Sum,

you'll notice that this box to the left

populated with some text.

This box is actually pretty useful.

So the first thing it shows you

is an example of what this expression

is going to be. I know expression

sounds likes a really fancy term,

if you've ever used a formula in Excel

it's basically that. It's telling the computer

what it needs to do.

In this case, just like Excel,

we've got the word sum,

which tells the computer

it's going to be summing different

values together. And then in parenthesis,

immediately after that, we have different

variables that are separated by a comma

and that's what tells the computer

to add x, y, and z things together

to create a new variable

or compute a new variable.

This also provides additional

extra content here, but we don't need to

worry about that. I've found this

is useful if you are stuck or something

isn't working right.

So we've got some selected,

we're going to be summing the items

of one, two, three, four, five, and six together