I would like some help on the following:

1) I am having trouble with finding the way to incorporate SD line (vertical) in the line graph in SPSS. Could you guide me to the right place?

2) I have ordinal variables (items), but if I added the scores of a few or several items to make up a factor or domains for example, the nature of the ordinal variables become more continous and can be treated as such in SPSS?

3) When I compare two populations (one with 150 people, and more normal and the other with 40 people with some illness) using t test (I guess I should use t test rather than z), how can I get the effect size (how much they differ) for certain variable? Should I enter into SPSS the Mean and SD from each population and then compare?

Please help me on these three things. Thank you.

(1) I'm not sure what you're referring to here....

(2) That should be OK - just clearly note in your report what you did.

(3) For either a t-test or z-test, I believe SPSS should provide the effect size within the output under the column called "Mean Difference"

http://academic.uofs.edu/department/psych/methods/cannon99/level2b.html

Thank you,
1) I am talking about the standard deviation (SD) line. I see some people present beautiful graphs (line) with vertical line for each X value. I just wonder if SPSS has the function.
3) Please forgive me for asking this again, but how do I enter and compare the data that are in separate file?

Those are called "error bars" - I'm pretty sure SPSS has that feature, because I've used that graph before.

To compare data from another file, I would just copy/paste the data into the same file - make new variables or case descriptions if necessary.

Thank you, Joh, I am impressed! I will look for the error bars.