I administered the same questionnaire to a sample of 800 but for each item, the wording presented to a participant was one of two variations based on whether they were told that their responses would would be anonymous or public (e.g. "do you feel obligated to sign your name in support of the petition?" v.s. "do you feel obligated to anonymously support the petition?"). This means that in SPSS, there are data for 2 versions of the same item where participants have a response value for one and are missing for the other (depending on their assigned condition).
Using the above example, I would like to consolidate the data for both versions of the same item so that i can analyse "obligation to support petition" as one variable, regardless of the wording. At the moment, "Obligation anonymous version" has 400 responses and 400 missing values, where every case with a missing value has a response on "Obligation public version" instead.
Could anyone please help me with this task? I have a total of 31 items, each with 2 versions of itself.