You conduct a case-control study to examine the association between having a pet turtle and salmonella. In your study, you recruit every one of the incident cases of salmonella that are reported to the NYC Department of Health over a period of 6 months. For your controls, you select a random sample of New Yorkers without salmonella using incidence density sampling (you select two controls per cases). You ask the cases and the controls if they have owned a pet turtle in the past month. You also ask about consumption of spinach in the past month, as this food item has been linked to salmonella. You end up with a sample of 564 people (188 cases and 376 controls)