According to the passage, the researchers compared the ability to dance of children who took dance classes to those who did not and concluded that dance improved their balance. It might also be the case that the children who took up dance had better balance even before starting the classes. It would be helpful to know how the two groups performed in terms of balance before the classes started to better evaluate the conclusion.

So, the correct answer should be It would be most helpful in evaluating the researcher's hypothesis to know whether the researchers tested the children's sense of balance prior to having taught dance to the children through the dance program.
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[quote="goodyear2013"]In an experiment, one thousand nine-year-old children were allowed to choose whether to participate in a program in which the researchers taught
them dance during the daily break from their lessons. Four hundred of the children chose to participate for at least one year. At the end of the year,
researchers found that the children who had participated had significantly better balance, on average, than those who had not.
The researchers hypothesized that dancing resulted in a sustained improvement in the children's sense of balance.

It would be most helpful in evaluating the researcher's hypothesis to know whether the researchers ___1___ prior to having __2__.

Select Researchers for the phrase that fills the blank labeled 1 in the given statement, and select Prior to for the phrase that fills the blank labeled 2 in the given statement to create the most accurate statement on the basis of the information provided. Make only two selections, one in each column.

1:Researchers | 2: Prior to
0 0 tested the children's ability to dance
0 0 designed a second experiment
0 0 divided the children into the two experimental groups
0 0 tested the children's sense of balance
0 0 taught dance to the children through the dance program

Hi, I found this question hard. In fact, not sure where to start with.
Can anyone explain this for me, please.

Hi goodyear2013
The passage says that, researchers "taught dance to childerne" and after one year they concluded that the children who had participated had significantly better balance, on average, than those who had not. And thus Dancing helped
Now as the result is based on the "average", if some of the children who took the program already knew dancing then the resulted average would stand incorrect.
Therefore Ans :
the researchers ___1.tested the children's ability to dance___ prior to having __2.taught dance to the children through the dance program__.

Hope it helps.

For the first one i got it correct
but second i got stuck between c and e.

Even C fits perfectly.
Prior to divide into 2 experimental groups will tell me how children who had participated had significantly better balance, on average, than those who had not .

Since we are talking about sustained improvement are we going with E ?
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IMO, C is incorrect because, it implies that comparing the two groups is still the best way to conclude whether the dance lessons led to an improvement. However, this is not the best method, as it may be the case that students who took lessons (group A) did not improve, but those in the other group (group B) declined in their ability. Or, it may be that group A declined in their ability, but it was still far better to begin with. E is a good choice, because it directly determines whether dance lessons led to an improvement by only focusing on group A.

GMATNinja I was wondering if you could help me with this.

I have issues understanding why E is better than C.

First, were 400 students chosen, and out of those 200 were given lessons, and the rest didn't? Or were the 400 given lessons and the rest of the 1000 didn't? I don't see where in the passage we can fully deduce this.

Either way, if we are weighting the kids before splitting into the 2 groups, isn't that better than weighting them before the dance starts? I mean, it's the same really... because if you weigh them before diving them into experimental group, you also weigh them before dance starts... and the earlier you measure weight the better, since then you can avoid situations were... for example, students self select... so students who have better balance, sign up for the classes...! This you would not detect if you weight the students after you have already split the group into the two experimental groups.

I'm pretty confused. :S

In an experiment, one thousand nine-year-old children were allowed to choose whether to participate in a program in which the researchers taught them dance during the daily break from their lessons. Four hundred of the children chose to participate for at least one year. At the end of the year, researchers found that the children who had participated had significantly better balance, on average, than those who had not. The researchers hypothesized that dancing resulted in a sustained improvement in the children’s sense of balance.

gmat800live, I don't mind weighing in on this one... except that I'm not 100% sure that it's an official question. If it isn't, I don't think it's going to be worth anybody's time. Do you happen to know the source of the question? goodyear2013 posted this in 2014, so s/he might have stopped monitoring this thread a long time ago.
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GMATNinja thank you so much! This was one of the questions I got wrong on GMAC official PrepTest 4! Definitely official !

Any clear reason why C is wrong for "prior"? Any experiment should have at minimum one treatment group and one control group. It's a requirement for validity sake.
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Think about this. The students CHOSE to dance. This causes bias. The people who chose to dance probably chose to because they wanted to. Maybe they danced before and therefore have better balance. So, checking their balance before the program will help understand what kind of boas was introduced which comparing results from before and after the dance lessons.

Yes, I did get this in my Official GMAC Practice Test 4 too.
Please help [quote="GMATNinja"]

Thank you.

Hmm, the other funky thing is that the updated question only has 4 options, so the option (C) that you're talking about is no longer available. Does anyone have a screenshot to confirm the actual options from the test? NCC?

The deleted option ("divided the children into the two experimental groups") is suspicious because the researchers didn't divide the children into two groups. Instead, the 1,000 children were allowed to choose whether to participate (400 chose to participate, so those 400 children were taught dance during the daily break from their lessons).

Otherwise, yeah, the important thing is measuring their balance before the daily dance instruction began. So if we ignore the semantic issue with the (perhaps unofficial or altered) answer choice (C), it seems like either (C) or the final option could work.

You could argue that the final option speaks more directly to what's important (that the balance testing happened before the dance instruction), so even if neither is inaccurate, the last one is probably a bit better. But I'd love for someone to confirm the actual options before wasting too much time discussing an option that may not exist!
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