Compute by hand: how large is the odds ratio (OR) of catching the flu for vitamin cversus no vitamin c? How large is the OR of catching the flu for no vitamin c versus vitaminc? Based on these odds ratios, does vitamin c decrease or increase the odds of catchingthe flu

To answer your question, we first need to have some data or a study that provides us with the number of people who caught the flu with and without taking Vitamin C.

The odds ratio (OR) is calculated as follows:

1. First, we need to set up a 2x2 contingency table:

Where:

• a = number of people who took Vitamin C and got the flu
• b = number of people who took Vitamin C and did not get the flu
• c = number of people who did not take Vitamin C and got the flu
• d = number of people who did not take Vitamin C and did not get the flu

2. Then, we calculate the odds of getting the flu for each group:

• Odds for Vitamin C group = a/b
• Odds for No Vitamin C group = c/d

3. Finally, we calculate the odds ratio (OR) as follows:

• OR for Vitamin C vs No Vitamin C = (a/b) / (c/d)
• OR for No Vitamin C vs Vitamin C = (c/d) / (a/b)

If the OR for Vitamin C vs No Vitamin C is less than 1, it means that taking Vitamin C decreases the odds of getting the flu. If it's greater than 1, it means that taking Vitamin C increases the odds of getting the flu. The same interpretation applies to the OR for No Vitamin C vs Vitamin C.

Without specific numbers, we can't calculate the exact ORs. However, this is the general process you would follow.