When do I need to weight cases in SPSS when doing a chi square independence test?

Some tutorials show data being weighted and some show just using cross tabs, entering your variables, clicking statistics, and choosing chi-square.





When does data need weighted? Thanks!When do I need to weight cases in SPSS when doing a chi square independence test?
You weight cases because it's easier sometimes.





If I know that I have 100 people in group A who chose option X, I could write 100 rows in my SPSS datasheet with an A in 1 column and an X in the other. Or I could write it once, and put in a weight variable - this tells SPSS to act as if the row has been repeated 100 times.