How to combine single Likert items into one scale?

[missle...@gmail.com]

Hello,

I have a very time-sensitive question:

I am replicating a theory that uses 12 Likert items to measure three latent variables (4 items per latent variable).
Also in my study I use these 12 likert items that measure three latent variables. Every latent variables is measured by 4 Likert items. For my research, I have to combine/sum these variables into one measurement. So hat I have three variables as a result.
My question/problem is: How can I combine these 4 Likert items into one scale, so that I have one number for each latent variable that I can use for my analysis?
Some extra information:
All the Likert item are measured on a 5-point-Likert scale.
I have already run Cronbach's Alpha in SPSS and the 4 items have a very high Alpha. Also, the "corrected item- total correlation" is high enough.

I want to use the three variables in a ordinal log regression analysis.

Your help is greatly appreciated!

[Bruce Weaver]

If you are asking how to compute sums and means, take a look at the following links:

http://libguides.library.kent.edu/SPSS/ComputeVariables
http://www.spss-tutorials.com/spss-sum-cautionary-note/

HTH.

[Elavarasi P]

hi anybody know this,

how to find mean

here my syntax
CTABLES
/VLABELS VARIABLES= q1_5_1 q1_5_2 q1_5_3 q1_5_4 q1_5_5 DISPLAY=LABEL
/TABLE center[c] >( q1_5_1[c] [ROWPCT.COUNT F40.0] +
q1_5_2[c] [ROWPCT.COUNT F40.0 ] +
q1_5_3[c] [ROWPCT.COUNT F40.0] +
q1_5_4[c] [ROWPCT.COUNT F40.0] +
q1_5_5[c] [ROWPCT.COUNT F40.0])
/CLABELS ROWLABELS=OPPOSITE
/CATEGORIES VARIABLES= q1_5_1 q1_5_2 q1_5_3 q1_5_4 q1_5_5 ORDER=A
KEY=VALUE EMPTY=EXCLUDE LABEL ='BASE'.