Produces a data frame that summarizes both the frequency and details of answer changes.
An answer change may involve one, many, or a combination of the following interviewer actions: answer changed, answer removed.
The summary reduces the answer change events for a question into a formatted string of the following format:
(order) (+/-) value, where order is the event order number in the paradata,
(+/-) indicates an addition/change ((+)) or a deletion ((-)),
and value shows answer value(s) due to that event.
The summary will consist of several such event blocks separated by a semi-colon (i.e., ;).
summarize_answer_changes(df)Data frame that is Survey Solutions' paradata
Data frame.