PT15.S2.Q03 - A certain strain of bacteria was found

lawschoolhopeful-4

I am a bit confused with this question. This is a classic cause --> effect stimulus and we are being asked to strengthen the cause and effect relationship.

To strengthen, there are three ways:
1/ Show that cause happens --> effect happens
2/ Show that cause does not happen --> effect does not happen
3/ Show that an alternate explanation is not responsible for both cause and effect

A/ What can't this be the third option? Doesn't the fact that there is no greater incidence of kidney disease for folks who have the bacteria in their stomach rule out the alternative explanation that kidney disease was not responsible for both the ulcer and bacteria?

E/ I understand that this is (no cause --> no effect) and is a strengthener, but I picked A since I was moving quickly in this section and to me, AC A seemed like an obvious alternative explanation that was being ruled out.

What am I missing?

Admin Note: Edited title. Please use the format: "PT#.S#.Q# - brief description of the question"

canihazJD

Saying no correlation between bacteria and kidney disease does not affect the relationship between the bacteria and ulcers. Even if kidney disease caused ulcers that doesn't mean bacteria doesn't.

Furthermore the lack of correlation doesn't "rule out" anything... we focus on correlation ≠ causation, but tend to forget things like correlation doesn't mean it's not causation, and lack of correlation doesn't mean you can't have causation.

You could make A strengthen... but we are after the best answer. The one that moves the needle the most on its own.

E is a direct strengthener. You want the answer that wins on its own without your help. Notice for A, you made the jump for them.

lawschoolhopeful-4

Got it. I guess my lapse was not realizing that no correlation also does not mean no causation. As such, you can't rule out it. That's a very good way of putting it.

AC E is a much obvious strengthener looking back. Thanks!