How would I go about answering this question? I'm stumped.
I'm no expert, but I would break the question down in correspondence to the 4 marks that are allocated to it. In general, I would focus on the main features that you know are a part of an epidemiological study and just link it to the scenario given by the question:
1. Create a large population sample of individuals with diverse backgrounds, including living in different areas, differences in age and gender, occupation, lifestyle, etc
2. Gather data on the eating habits of those affected and those not affected, paying particularly attention to if fish is the main food source or meat, due to the recent chemical factor that had started up nearby.
3. Gather data on the location the individuals affected and not affected live: i.e if they live near the far side of the bay where the chemical factory is situated
4. Compare the data gathered on the affected and control groups and interpret for trends: i.e: similarities, differences. You could also potentially make a prediction as to what the cause of the symptoms may be, which, judging from the information provided, you could hypothesise that it is the chemical run-off from the chemical factory into the water that the fish, which is the main food source for town, live. Thus, individuals who eat a diet mainly of fish have contracted the disease.
What HSC paper is it from?