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Hi all, I have a couple LR related questions. These two concepts are a little ambiguous for me to understand. Please clarify. Any response is greatly appreciated! Thanks a lot in advance.

1. What are the qualities of a valid survey/experiment/study?
(or when do you know when the stimulus is committing the "representativeness" flaw?)

I understand that whenever you see stimulus with survey/experiment/study wording, you should ask
1) right people? 2) enough people? 3) enough time?

But are there more qualities to consider?

2. If a stimulus says that in a specific country, A and B are related by stating that when A increases, B also increases, then can the answer to a weakening question be a counterexample? (ie: in another country, when A increased, B decreased)
What could be an answer to a strengthening question in accordance with the hypothetical stimulus above?

My questions may not be the most articulate ones, but please help!
Thanks

kky215 wrote:Hi all, I have a couple LR related questions. These two concepts are a little ambiguous for me to understand. Please clarify. Any response is greatly appreciated! Thanks a lot in advance.

1. What are the qualities of a valid survey/experiment/study?
(or when do you know when the stimulus is committing the "representativeness" flaw?)

I understand that whenever you see stimulus with survey/experiment/study wording, you should ask
1) right people? 2) enough people? 3) enough time?

But are there more qualities to consider?

2. If a stimulus says that in a specific country, A and B are related by stating that when A increases, B also increases, then can the answer to a weakening question be a counterexample? (ie: in another country, when A increased, B decreased)
What could be an answer to a strengthening question in accordance with the hypothetical stimulus above?




My questions may not be the most articulate ones, but please help!
Thanks

For 1. also consider the methodology that was employed by the survey. If it in someway favors a particular group to induce a certain outcome then that may also be a reason it was flawed.

For 2. you would have to be more specific regarding the details of the argument.

The 'representatives' flaw i think you're referencing specifically speaks to a sample that does not or is not likely to represent the group as a whole. For example, a research conducted for finding out if people in general like romantic comedies would have selected an unrepresentative group if they selected 'macho' men. Macho type guys usually don't like those movies, but they aren't likely to be representative of the whole group of people; the group would be better represented if the researchers chose people of all types.

There are many different types of flaws the LSAT can use with samples. Have you tried the Power Score bibles?

kky215 wrote: 1. What are the qualities of a valid survey/experiment/study?
(or when do you know when the stimulus is committing the "representativeness" flaw?)

I understand that whenever you see stimulus with survey/experiment/study wording, you should ask
1) right people? 2) enough people? 3) enough time?

But are there more qualities to consider?

Nearly every time you see a study/survey done in an LSAT question, there's some type of sampling fallacy.

Here's what you need to evaluate:
1) Was the sample random and likely to represent the group it purports to represent?
2) Was there any reason for the people asked to lie, or were the questions outside their understanding?
3) Is the conclusion logically related to the questions asked?

Those are the three things the LSAT cares about. What you list (right people/right time) has to do with 1 and 3 (because if I ask people at the wrong time, the conclusion isn't logically related). Your second one is a common red herring on the LSAT. It is very, very rarely the case that the LSAT will give you a bad survey because the sample size wasn't large enough. For that to be the correct answer, one of two things has to be met:
1) The sample size is in the single digits
2) The sample size AND the overall group size that it purports to represent are both given, and the sample size is ridiculously small (think less than 1%).
Both have happened, but it's very, very rare that that's the correct answer. Avoid it unless one of the two criteria are met.

2. If a stimulus says that in a specific country, A and B are related by stating that when A increases, B also increases, then can the answer to a weakening question be a counterexample? (ie: in another country, when A increased, B decreased)
What could be an answer to a strengthening question in accordance with the hypothetical stimulus above?

There's no way I can answer this with the details given; you'd have to reference something specific.