Dear colleagues, I have a card sort research instrument that I am planning to change into a questionnaire for easier filling in and analysis. I have 64 items. I previously used a card sort to control the number of items placed in 4 different response categories so that they were balanced (8, 24, 24 and 8). I am planning to replace the 4 categories with 7 point Likert response scales. However, I still want to measure relative responses. Is it acceptable to standardize the responses before carrying out an Exploratory Factor Analysis? What literature is there on this subject?

To be specific, if the Likert response scales were scored 1 to 7, standardizing the responses would mean multiplying each of the scores by 4x64 then dividing them by the sum of the 64 original scores.