Problem
Dr. Ajaz and colleagues are studying the impacts of SARS-CoV2 (the virus that causes COVID19) on cellular metabolism. Previous work found that SARS-CoV-2 RNA and proteins localize to mitochondria and hijack the host cell's mitochondrial function. Dr. Ajaz and team want to see how COVID19 infection impacts metabolism of a specific type of immune cell found in the blood. They collected cell samples from healthy controls (HC), COVID19 patients, and patients with chest infection but with a negative COVID test. They get the below data (note: this is real data from a real publication). What is Dr. Ajaz's dependent variable?