I have a question from the 2016 paper Q 2 bii)
So the relative risk calculated in the marking schedule is the risk of Jazz being diseased over the risk of Beauty being diseased. We compare this to the RR of diseased depending on the growing method.
I don’t understand why we are calculating this RR because by doing it this, we are determining how many times more likely it is for Jazz to be diseased compared to Beauty, and we compare this to how many times more likely it is for conventionally grown to be disease compared to organically. When the question in asking how many times more likely it is for the type of apples to cause disease compared to the growing method.
The way I worked out the problem was by finding out the risk of Jazz variety + risk of Beauty variety being diseased.
52/890 + 128/310 = 0.4713 (4d.p)
I then worked out the risk of organically grown+ risk of conventionally grown.
122/640 +58/560 = 0.2941 (4d.p)
I then compared the risk of these.
0.4713/ 0.2941 = 1.602
Therefore apples are 1.602 times more like to be diseased because of variety compared to the growing method.
So my answer is incorrect, any kind of clarity or insight would be really useful for me!