Im currently rethinking my statistical design after running into a few roadblocks.

My current BSc research is on the effects of perfectionist concerns/strivings And ineffective/effect coping strategies on injury occurrence (and potentiall frequency).

To measure perfectionist concerns, I have collected data using a multi measure approach utilising a subscale from the multidimentional inventory of perfectionism in sport (MIPS) and a subscale from the sport multidimensional perfectionism scale (SMPS).

The MIPS has 5 items for every scale whereas the SMPS has 8 for perfectionist concerns, and 7 for the perfectionist striving. When combining these to give me an overall perfectionist concerns/strivings scores, should I use Z scores or should I just combine them together?

relatively new to statistics so any information will be greatly appreciated.