Thank you for your reply, unfortunately I have read and re-read the links thoroughly and still don't know how I am meant to compute this.

I only have these four numbers.

The 38.5% is out of 52 participants.

The 12% is out of 114 participants.

I am using SPSS but I don't know how to arrange the numbers to run the test. It is very very frustrating!

You can do this in Excel (sorry I don't know SPSS). A very simple-minded Excel worksheet is attached, pardon its look.

You know that 38.5% of 52 participants = 20 are "successes" in row 1

You know that 12% of 114 participants = 14 are "successes" in row 2

(See the ACTUAL table, rows 1-3)

Thus you know that 34 of 166 participants (20.5%) are successes overall. So using this overall % of successes, you can determine the EXPECTED table (see rows 5-7)

eg 20.5% of 52 participants = expected 10.6506 "successes"

and 20.5% of 114 participants = expected 23.3494 "successes"

Chi-square test compares the actual successes vs expected successes in row 1, and in row 2 (alternatively, you can say it compares the actual non-successes vs expected non-successes, since successes + non-successes = participants).

Excel has a CHITEST function (see cell A12).