I'm very new to statistics and I've been asked to create a time series model in SPSS. I've taken a list of articles from one journal, each categorized by their main topic (topics have been numerically coded). The journal has been reanalyzed every 5 years.
I'm supposed to determine how these topics would vary with time, but I'm not sure how to input this into the Forecasting dialogue, and anyway the 'Topics' variable doesn't even denote real numerical value, which seems to be the case for every forecasting tutorial I've read. Is time-series even the best option for this kind of data?