Q13 - Recent research indicates that

[chungyesol]

I picked B, but i am not sure why it is B. Could anyone go over each answer choice as to why they are wrong or right? Thanks in advance!

[griffin.811]

Argument: Low levels of F lead to high levels of H which leads to blocked arteries. Since Fruit is high in F it reduces risk of stroke.

This boils down to: Fruit reduces risk of stroke because it is high in Folic acid.

If this is the case, then high levels of folic acid should reduce risk of stroke, otherwise the argument above is flawed. After all, how could that argument be made if "low risk of stroke is NOT associated with increased folic acid?"

A - Opposite of what we are told. Passage says high levels of H lead lead to Heart attack. (well to blocked arteries, but we have to assume blocked arteries and heart attacks are interchangeable here).

C - Same exact thing as A
D - Opp again. We are told HIGH levels of F are correlated with low risk of heart attack.
E - Scope; We don't know COMPLETE PREVENTION, just that we can REDUCE our risk.

[ohthatpatrick]

Nice response.

I'll just add to the conversation that I like to dumb these things down in terms of good/bad.

More 'folic acid' means less 'stroke'.

So,
HIGH folic acid: good
LOW folic acid: bad

LOW folic acid means HIGH homocysteine
HIGH homocysteine means more blocked arteries.

so
LOW folic acid | HIGH homocysteine | MORE blocked arteries

HIGH homocysteine: bad
LOW homocysteine: good

(A) more stroke (bad) is correlated with LOW homocysteine (good)

(B) decreased stroke (good) is correlated with HIGH folic acid (good)

(C) more blocked arteries (bad) is correlated with LOW homocysteine (good)

(D) less blocked arteries (good) is correlated with LOW folic acid (bad)

(E) "prevented" is too extreme

(B) is the only answer that pairs 'good' with 'good' or 'bad' with 'bad'. The other three give you a mismatch of good/bad.

Hope this helps.

[chunsunb]

But isn't negative correlation also correlation; and hence A B C and D are all correct? I'm trying to understand LSAT's usage of the word correlation.

[kkate]

But isn't negative correlation also correlation; and hence A B C and D are all correct? I'm trying to understand LSAT's usage of the word correlation.

I was wondering the same thing too....

(Since I just watched Forks over knives)

1. chance of getting cancer is correlated with meat consumption --> the more you eat meat, the higher chance you getting cancer. The odds of cancer depends on your meat consumption. In other words, meat consumption causes cancer. believe it or not.

But this is completely different from

2. meat consumption is correlated with my chance of getting cancer --> Meat consumption is not dependent on me getting cancer. Cancer does not cause meat consumption.


Can someone let me know if I'm going anywhere with this logic. My head hurts I'm just going to go make myself a salad.

--

Is it suggested that we just go ahead with good/bad approach (as demonstrated by Patrick) in similar situations with correlation everywhere in the answer choices?

[ohthatpatrick]

Sorry, my original post was a little confusing. I certainly do not handle CORRELATIONS by regularly using "good/bad".

I was really referring to technical science-y stuff that's just hard to hang onto in our brains. If I'm reading an RC passage about different types of bacteria, instead of trying to say the specific species names, I'll stamp them "bad guy bacteria" (if harmful) and "good guy bacteria" (if helpful).

I think positive correlation means as X goes up, Y goes up.
A negative correlation would be more like as X goes up, Y goes down.

Those are both correlations.

What I was showing with my answer choice breakdown was simply reflecting whether the argument had told us something was good or bad. It would be logical to say, "when you do this good thing, good things happen" and logical to say "when you do this bad thing, bad things happen". It would be surprising to see a mismatch, like "when you do this good thing, bad things happen" (then why are we calling the first thing GOOD?)

Let's just lay out the causal sequences (I'm make it look like a conditional chain, just for visual simplicity)

More fruit/vegs -> more folic acid --> low homocyst --> less blocked artery / strokes
or
Less fruit/vegs -> less folic acid -> more homocyst -> more blocked artery / strokes

(A) more stroke is in the chain with MORE homocyst, not low levels
(B) less stroke is in the chain with more folic acid. CORRECT
(C) more blocked artery is in the chain with MORE homocyst, not decreased levels.
(D) less blocked artery is in the chain with MORE folic acid.
(E) Nothing ever talked about PREVENTING stroke.

kkate, unfortunately I'm not smart enough about statistics to know if
X is correlated with Y
means the same thing as
Y is correlated with X
but I think they are interchangeable.

When we say X is correlated with Y, we mean there is SOME association that the more you see X, the more you'll see Y.

If you picture these as x,y pairs on a graph, they don't have to be a perfect line (I think that would be a correlation of 1, the highest possible association) ... but they could be a scatter plot with some sense of pattern.

It seems pretty tricky for me to think how you could have a statistical association in one direction that wouldn't also apply in reverse, because it's the same set of data points in both cases.

Saying that X and Y are correlated / associated is not proof of any causal relationship between X and Y.

But it is support that there MAY be some causal relationship between X and Y.

[z.zhu0601]

Hi, I am a little confused about the relationship between Fruits/Vegitables and Stroke.

Since the stimulus says "fruits and vegetables by middle-aged people reduces their susceptibility to stroke", does it mean there is causal relationship between them? Because of the word "reduce"?

For the rest of the ideas: folic acid, homocysteine etc., relationships among them are just correlational right?

Thank you in advance for the answer.

[Emmeline Ndongue]

Hi, I am a little confused about the relationship between Fruits/Vegitables and Stroke.

Since the stimulus says "fruits and vegetables by middle-aged people reduces their susceptibility to stroke", does it mean there is causal relationship between them? Because of the word "reduce"?

For the rest of the ideas: folic acid, homocysteine etc., relationships among them are just correlational right?

Thank you in advance for the answer.

There's one more causal relationship

correlation≠causation
what the stimulus gave us:
1. "increased consumption of fruit and vegetables" causes "susceptibility to stroke" to drop (The researchers tried to find out why)
2. fruit and vegetables are rich in folic acid
3. "low levels of folic acid" correlated with "high levels of homocysteine" (this means "high levels of folic acid" correlated with "low levels of h." this is stats.)
4. "homocysteine" causes "blocked arteries"

in order to explain 1. mentioned above, we need: "low levels of homocysteine" causes "susceptibility to blocked arteries" to drop, and "susceptibility to blocked arteries" drops causes "susceptibility to stroke" to drop. (These are the 2 assumptions that have to be made)

So, with these 2 assumptions, we have "low levels of homocysteine" causes "susceptibility to stroke" to drop, and we know that "high levels of folic acid" correlated with "low levels of h.", so now we can say that "high levels of folic acid" correlated with dropping of ""susceptibility to stroke"

it's dumb to do this kind of analysis. this question should only take me 40secs, anybody can get it correct relying on their instinct.