Two readings of a lighting change
Separating a figure that is agreed on from a conclusion that is not.
Paired texts
Text 1: Replacing sodium street lamps with narrow-spectrum LEDs removes most of the ultraviolet and blue light that draws night-flying insects. Over two years on eighteen streets we counted 62 percent fewer moths at each converted lamp than at the sodium lamp it replaced. On this evidence the case for conversion is straightforward.
Text 2: Bell's per-lamp figures are not in dispute. What they leave out is how many lamps there now are. The councils that converted also took the opportunity to light nine streets that had previously had no lamps at all, and to extend lighting from midnight through to dawn. Counted per lamp, attraction fell. Counted per street, and across the whole night, it did not. I would qualify Bell's conclusion rather than reject it: the conversion is a genuine improvement in lamp design that has so far been spent on more lighting.
Answers in order, explanations withheld, and a report on where the chain broke.
- 34.1Central ideasFoundation
What does the 62 percent figure in Text 1 compare?
- AMoths at one converted lamp against moths at the sodium lamp it replaced.
- BAll the moths in the eighteen streets before and after conversion.
- CMoths at converted lamps against moths away from any lamp.
- DMoths counted before midnight against moths counted after midnight.
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Moths at one converted lamp against moths at the sodium lamp it replaced.
Text 1 says "at each converted lamp than at the sodium lamp it replaced". It is a per-lamp comparison, and the whole disagreement that follows depends on noticing that.
- 34.2Words in contextStandard
Builds on: Nothing earlier — but the answer decides how you read question 3, so getting it wrong tends to cost two questions rather than one.
As used in Text 2, "qualify" most nearly means
- Ato limit the scope of
- Bto reject outright
- Cto endorse
- Dto become eligible for
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to limit the scope of
The sentence sets "qualify" against "reject", so it cannot mean reject; and the author spends the paragraph narrowing Bell's claim rather than agreeing with it. The eligibility sense is the everyday one and has no work to do here.
- 34.3Text structure and purposeChallenge
Builds on: Question 1, which established that the agreed figure is per lamp, and question 2, which established that the author is narrowing rather than rejecting. Read "qualify" as "reject" and the fourth choice starts to look right.
What does the opening sentence of Text 2 accomplish?
- AIt grants the measurement so that the disagreement can be placed somewhere else.
- BIt casts doubt on how carefully the counts were taken.
- CIt signals that Text 2 will reach the same conclusion as Text 1.
- DIt concedes a minor point in order to dismiss the study as a whole.
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It grants the measurement so that the disagreement can be placed somewhere else.
Accepting the per-lamp figure clears it out of the way, which is what lets the rest of the text argue about the number of lamps instead. The author is not doubting the counting, not agreeing with the conclusion, and not dismissing the study.
- 34.4Cross-text connectionsChallenge
Builds on: Question 3. Once the opening sentence is read as a concession, the point of agreement is already located: it is whatever that sentence conceded.
Which statement would both authors accept?
- AA narrow-spectrum LED draws fewer insects than the sodium lamp it replaces.
- BThe conversion reduced the total number of insects drawn to street lighting.
- CStreets that had no lighting should have been left unlit.
- DThe eighteen-street study was too small to support any conclusion.
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A narrow-spectrum LED draws fewer insects than the sodium lamp it replaces.
That is Text 1's finding and the thing Text 2 opens by granting. The second is precisely what Text 2 denies. The third goes further than Text 2 says — it points out the extra lighting without recommending its removal. The fourth is nobody's position.