Q21 - When a person with temporal

[skapur777]

I wrote question 22 for this when it is really question 21. It seems like another question from another section is listed as 21 here.

I put down B for this one. I knew A and C were wrong since we don't know the reliability of the EEG (such as how right it is over how wrong it is).

With respect to B, since I figured that evidence of an abnormal electrical impulse is a necessary condition of temporal lobe epilepsy, then a positive reading could indicate the presence of other forms of epilepsy. Now I believe this is wrong for two reasons:
1. the word "also" sticks out at me, as if the person has temporal lobe epilepsy for sure and perhaps others.
2. we don't know if other kinds of epilepsy has abnormal electrical impulses as a symptom (even though they do in real life, but I guess ignore this?)

And E is incorrect because again we have no way of seeing how reliable wrong and right readings are. This answer is hinting at the chance being 50/50.

Is this correct?

[geverett]

Hey the 2nd point you made is the one that makes the most sense to me. Also, remember that we must suspend real world information and just take what they give us in the stimulus. Just because we know that all epileptic seizures create electrical impulses does not mean that we can infer that based on what we have been given in this stimulus. The stimulus limits the scope of the kind of seizures we are talking about here to "temporal lobe epilepsy". With that in mind we can eliminate answer choice (B) just on the grounds that we know nothing about any other kinds of epileptic seizures except those pertaining to temporal lobe epilepsy.

Alright, here is how we get to D. The stimulus says that these electrical impulses can "often, but not always" be detected through an EEG. The phrase "often, but not always" is intentionally ambiguous and basically means anywhere from 1% of the time to 99% of the time an EEG will identify the presence of electrical impulses that are there. It's another way of saying "sometimes the test detects the presence of electrical impulses that are there, and sometimes the test does not detect the presence of electrical impulses that are there." What we do not know is how often it correctly identifies them and how often it says they are not there when they really are. Answer choice D gets at just that.

A, C, and E are all wrong because they try and force you to take the ambiguous phrase "often, but not always" and make it say something that it's just not saying - which is that there is a definite ratio of probability that you can infer from the statement "often, but not always" If you need more clarification on this point check out the Manhattan LR guide and the section on "modifier words"

[giladedelman]

Awesome explanation!

And, thanks for pointing out the misplaced post; I've moved it and changed the title of this one. Thanks for the discussion, guys!