This afternoon, I was analysing the market research surveys that the other members of my video project group had carried out (it was agreed they'd do the research and I'd do the paperwork). On one of the surveys, I became confused when the respondent had circled multiple - and often contradictory - options on the multi-choice form.
After the confusion, the form then seemed like trolling but once I inspected it more closely, I realised that the respondent had circled the options that didn't apply to them and left blank the ones the did. As such, it became clear that anything they had left unmarked was to be taken as an option that applied to them.
While it was annoying that the person had filled out the form in this manner, they had nevertheless given valid answers and it was simple enough to decipher once I'd worked out the pattern.