I am new to the NDCC, working with a senior officer on an investigation. Cecilia Young suggested I contact you about an investigation in which we are studying an outbreak where many people became sick after eating at a large banquet at the Tip Hotel.

Our team did a case-control study to determine which of the menu items were associated with getting sick. (I don't really know why we chose a case-control versus a cohort study... and I'm not even sure the difference, so that's my first problem.) We calculated the Odds Ratios and I was asked to write up a summary of the findings, now that the team has been assigned to another urgent case. But I need some help since I’m not really sure what ORs tell me.

Here are the Odds Ratio results of our study:

Hot Table:

• Beef (5), Gravy (2.5), Potatoes (1.1), Vegetables (1.2), Fish (1), Chicken (.9) and Lasagna (1.2)
  

Cold Table:

• Pasta Salad (1.1), Chocolate Cake (1.3), Carrot Cake (1.2), Green Salad (1.1), Rolls (1.3)
  

Drinks:

• Soda (1.1), Tap Water (1), Apple Juice (.9), Red Wine (2.3)

At this point, I really need you to help me understand why my team chose a case control study over a cohort study, and what these Odds Ratios tell me about our study. How do I know which food(s) are the likely culprit(s)?

Thanks,
Andy