#9 - In one study of a particular plant species, 70 percent

[Dave Killoran]

Complete Question Explanation

Resolve the Paradox—#%. The correct answer choice is (D)

The stimulus is relatively straightforward. The paradox here is simply that in two studies of a particular plant species in a similar geographical area, the reported proportion of patterned stems differed. One study showed a rate of 70%, the other study 40%. In crafting your prephrase, look for an answer choice that could explain the disparity between these two reported figures.

This question is a good example of a common theme to paradoxes on this test. Note that the difference here is in the reported number of patterned stems, not necessarily the number that actually exists in nature. Whenever you have a paradox involving reported data, it usually leaves open the possibility of an error or an anomaly in the data as an explanation of the paradox.

Answer choice (A): This can be a tricky answer choice, and around 25% of students select this answer. The attraction is that this answer might suggest to a student that the studies were conducted at different times of the year (which would be a valid explanation for the difference), but that isn't the case. Since the answer only tells us when the first study was conducted, we can't infer that the second study was done at a different time. Thus, if you were attracted to (A) in the belief that the first study was conducted at an "optimal" time of year for the best results, this answer doesn't work because the second study could have been conducted at that time as well.

Of equal importance, the "most populous" information (which is about actual numbers) doesn't impact the stimulus since the stimulus is about percentages. Here the test makers have tricked students into confusing numbers vs percentages. In direct terms, even if there were the greater number plants in the first study ("most populous"), the percentage of those plants with patterned stems would still be the same, and in this case was still higher. In short, a higher total number of plants should not affect the percentage of those plants with patterned stems. Consider the following very rough example:

• In one of the History 205 classes at my school, 70% of the students failed. In another section of the History 205 class at my school, only 40% of the students failed.
  
  Answer choice (A): The first class had more students.
  
  Does the fact that there were more students (#s) impact or explain the failure rates (%s)? No, and by analogy this helps show why (A) is wrong in this problem.

Always be careful when dealing with percentages on Logical Reasoning questions. The test makers like to play on the distinction between totals and percentages. Higher totals do not automatically lead to higher percentages, and higher percentages do not automatically lead to higher totals.

Answer choice (B): This answer choice, if true, would also fail to resolve the discrepancy between the two percentages. The percentages here were both associated with one particular plant species. So even if the first study also included data from additional plant species, that does not explain why the percentage for the original species was so much higher in the first study than in the second study.

Answer choice (C): Similar to answer choice (A), this answer choice suggests that there is a higher total number of plants in one of the studies. The total number of plants should not have any effect on the percentage of those plants with patterned stems.

Answer choice (D): This is the correct answer choice. If the first study used a broader definition of “patterned”, then it is likely that there would be more plants that fit that broader definition. This could easily explain why the first study had a much higher percentage of “patterned” stems than the second study.

Answer choice (E): This is actually an Opposite Answer. The answer choice appears to deepen rather than resolve the paradox. If the second study focused on patterned stems, but the first study did not, that seems to suggest that the second study would have a higher proportion of patterned stems than the first study. However, we know clearly from the stimulus that the opposite is true: the first study had the higher proportion of patterned stems. This answer makes the numerical situation in the stimulus even more puzzling and therefore does not help to resolve the paradox.

[okjoannawow]

Hi,

Can someone explain why A is an incorrect answer? I can't really make sense of the admins explanation above. I understand why D is the answer, it was one of my Contenders while taking the section.

Thank you!

[Dave Killoran]

Hi Joanna,

I've expanded the explanation for answer choice (A) to help make it clearer for you, but the point being made there is that more plants doesn't mean the percentages changes or make a difference

[okjoannawow]

Thank you so much Dave!! Your expansion was great, it makes a lot more sense now why A was incorrect. Thanks again!

[LSAT student]

Hi,

I still need help with why (D) isn't incorrect. The justification for why (A) is wrong is that it gives us information about the first study by saying "The first study was carried out at the time of year when plants of the species were most populous," while saying nothing about the second study.

But answer (D) also only talks about the first study and says nothing about the second. Lastly, if we were to rule out (A) on the basis that it's talking about numbers and not percents, then what about answer (C) is incorrect, because it specifically talks about percents, "15 percent more individual plants than the first study"?

Please help, especially with how answer (D) isn't doing the same thing as (A) when it comes to the studies they discuss.

[Jeremy Press]

Hi LSAT Student,

Answer choice D necessarily talks about both studies by using comparison language. Since it says the first study used a "broader" definition, that necessarily means the second study used a "narrower" definition. Thus, the answer implicitly addresses both studies (solving the deficiency in answer choice A). That comparison language isn't present in answer choice A, so I can't take from answer choice A any additional information about the second study. Maybe the second study was conducted at the same time of year. Maybe it wasn't. The language of answer choice A can't get me there, either way.

Again in answer choice C, it's because of the comparison language used that the figure being referred to is only telling us about "total numbers," and not about a fraction (a percentage) the way the stimulus is. If I say that Class A has 15% more students than Class B, I'm really just talking about the comparative number of students in those classes, right? Now, I can't tell from that phrase exactly what that number is, but any way you slice, I'm just saying that there are more students (on a numbers basis) in Class A than Class B (115 in Class A to 100 in Class B; or 230 in Class A to 200 in Class B, etc.). Same with answer choice C--it's really just talking about the relative number of plants used in each of the studies. But that relative number can't by itself affect the percentage (the fraction of the number of plants studied) that have patterned stems. Put differently, answer choice C is only speaking to the denominator (number of plants studied, across the two groups) without speaking at all to the numerator (the number of plants with patterned stems).

I hope this helps!

[TryingToImprove]

Hi Jeremy Press,

You stated that "Answer choice D necessarily talks about both studies by using comparison language. Since it says the first study used a "broader" definition, that necessarily means the second study used a "narrower" definition." But doesn't, answer A do the same thing? Answer A states that "The first study was carried at the time of the year when plant species are the most populous" which indirectly states that the second study was carried at the time of the year when plant species were not the most populous.

If that is not the case, then just because the answer states that "The first study used a broader definition", it does not mean that the second study did not also do the same. The second study could have also used a broader definition. If we can't make the assumption for answer A, we shouldn't be able to make the assumption for answer B, as the wordings are the same. Or, maybe I am misunderstanding something.

[Robert Carroll]

Trying,

There's nothing in answer choice (A) or in the stimulus which entails that the studies were conducted at different times of year. So there is no comparison possible. Answer choice (D), on the other hand, uses the comparative adjective "broader". That has to be broader than the second study. So I don't agree that each answer has the same amount of comparative language.

Further, Jeremy's point about comparative language, which I think is valid, isn't necessary to get rid of answer choice (A). As Jeremy further discusses, info about absolute numbers, as given in answer choice (A), won't solve a point about percentages. That there are more plants during one study versus another does nothing to explain why a differing percentage of that larger absolute number had a certain quality.

Robert Carroll

[queenbee]

Hi
With respect to answer A, I read the explanation regarding the percentage "trap" where the analogous example was 2 different History 205 classes. In the stimulus, the geographical region was approximately the same, so effectively, the history classes would need to be the same if that analogy were to be used (a few students dropped the class, a few student joined late)

For answer choice D, it seems like we would need to assume that the study was from a different group of people conducting the test, or, the criteria for the second study was different from the first, otherwise why would we assume that they were interpret "pattern stems" differently or include a broader range.

It seems like we have to assume something, so why not assume that they studies were taken at different times (winter and spring)?

If there was an answer indicating that the 2 studies in question were evaluating different things, that would have been a better answer because i could at perhaps assume that the criteria to be considered "pattern" was more strict in the first study. I am struggling whenever we need to "imagine" what else could be a cause.

What in this passage would make me "imagine" the correct scenario?
Thanks for the help.

[Adam Tyson]

First, focus on this aspect of Dave's answer at the top of the thread:

This question is a good example of a common theme to paradoxes on this test. Note that the difference here is in the reported number of patterned stems, not necessarily the number that actually exists in nature. Whenever you have a paradox involving reported data, it usually leaves open the possibility of an error or an anomaly in the data as an explanation of the paradox.

The so-called "reporting paradox" is one where reports would seem to conflict with reality. The plants shouldn't be different, but reports say they are, so maybe something in the reporting has changed? An error, a different standard for reporting, something like that.

In this case, a broader definition of "patterned" would have to mean that more plants would be called patterned than in the first study. If not, then it wouldn't be a "broader" definition, would it? That alone, with no other information, could explain the different results in the two reports. We don't need to assume different people did the study, and we don't need to assume different criteria because the answer SAYS there is a different criterion. The definition of the thing you are looking for IS part of the criteria!

As to your concern about the example Dave gave for why A is wrong, imagine a slight variation on that same example. On Monday, I looked in the classroom for History 205 and saw that 70% of the students were wearing flannel shirts, but on Tuesday I looked in to the same exact class and saw that only 40% of the students had on flannel shirts. To explain that difference, it would accomplish nothing to talk about how many students were in class each day, because numbers do not prove percentages. If there were 40 students in class on Monday and only 30 students on Tuesday, that would tell me nothing about the lower percentage of flannel shirts on Tuesday. It might help explain fewer flannel shirts, but not a lower percentage of whatever total happened to be there.

If the paradox is about percentages, answers about the total number are a distraction and a trap. If the paradox is about total numbers of something, answers about a percentage of those things are traps. Don't confuse numbers with percentages! If you have our course book, check out Lesson 9 for more on these ideas, and if you have the LR Bible there is a whole chapter on Numbers and Percentages to help you deal with these common flaws, paradoxes, and traps.