To get a
conceptual idea of how this works consider the following example:
Var1
Var2
Var3
scale
1
4
1
6
4
1
1
6
3
3
2
8
2
3
2
7
Notice that the value for each observation on the scale is equal to the sum of the values of the
three variables from which it is composed.
There are a few criteria for the variables you can use
to construct a scale:
o
All variables in the scale must have the same range of potential values
o
All variables in the scale must be positively correlated with each other
o
All variables in the scale, theoretically, must measure the same underlying
construct
o
The Cronbach’s alpha test statistic must be reasonably high (>.6 or so)
If all of these conditions are met the scale should be a reasonably valid measure (The higher the
values from which the variable is composed, the higher the value of the scale).
Let’s practice
with some variables from this data set: conpol, congov and conciv.
These variables measure
confidence in the police, the government and the civil service, respectively.
Before we begin, tab
each variable.
Now complete the following questions to confirm that these variables are appropriate for scaling.
a.
Do the variables have the same range of potential values?
What is the range?
No the variable do not have the same range of potential values.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Documentb.
Check to see if the variables are all positively correlated.
Before we do that we need to
make sure there are no anomalous values in the variables that need to be recoded as
system missing.
The data in this lab should be clean, but you always want to make sure
before proceeding.
Once each variable is clean (you should confirm this) produce a correlation table of the
three variables.
Use the command corr conpol congov conciv.
Copy and paste the
correlation table into the output sheet.
c.
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '13
 JoeDiGrazia
 Sociology, Control key, output sheet

Click to edit the document details