Use of Evidence > Logical Completion
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SAT Reading & Writing › Use of Evidence > Logical Completion
On a blueberry farm, researchers ran a controlled experiment across matched plots during peak bloom. In some plots they fitted mesh bags over flowers to exclude insects; in others, flowers were left unbagged. Wind speed and weather were recorded and did not differ meaningfully among plots. Fruit set was high in unbagged plots but dropped sharply in bagged plots; in a third condition, bags with openings large enough for bees but not for larger animals restored fruit set to the level of unbagged plots. No fertilizer or irrigation changes occurred during the study. The pattern indicates that, in these plots under these conditions, successful pollination depended in part on _______.
Which choice most logically completes the text?
higher fruit set attracting more bee visits.
all farms without wild bees failing to produce fruit.
wind alone fully explaining pollination outcomes.
the presence of wild bees.
Explanation
Excluding insects lowered fruit set, and allowing bees back restored it, so bee presence is required. The other answers either reverse causality (A), overgeneralize beyond the study (B), or contradict the evidence by ignoring bees (C).
Two job-training programs, A and B, were evaluated using random assignment of 800 applicants. Both programs provided the same classroom curriculum, instructor roster, and schedule; only A added weekly one-on-one mentoring and a modest stipend. Six months after completion, 64% of A participants were employed compared with 54% of B participants, a difference that remained after controlling for age, prior experience, and local unemployment rates. Dropout rates and job search hours did not differ between groups. Because the programs were otherwise identical and assignment was random, the most justified conclusion is that _______.
Which choice most logically completes the text?
at least one feature unique to Program A contributed to higher employment.
stipends, and not mentoring, are solely responsible for the effect.
higher employment among A participants led program staff to add mentoring.
any program that offers both stipends and mentoring will outperform others.
Explanation
Random assignment and identical curricula isolate the difference to features unique to A. The other options speculate beyond the data (B, D) or reverse cause and effect (C).
A museum tested email subject lines for an upcoming exhibition by randomly sending 40,000 subscribers either a generic subject line or a personalized one using recipients' first names. Open rates rose from 21% (generic) to 31% (personalized), and click-through rates mirrored this increase. However, ticket purchases and in-person visits during the campaign period were statistically indistinguishable between groups, and the website's checkout process and pricing remained unchanged. The test was run for only this exhibition and used the same send times for both variants. Consequently, in this test, personalization of the subject line alone _______.
Which choice most logically completes the text?
increased online sales for other exhibitions later in the year.
did not change the rate at which recipients visited the museum.
caused prices to appear more attractive to recipients.
will reliably boost ticket purchases for all future campaigns.
Explanation
Visits and purchases did not differ, so subject-line personalization did not change visit rates in this test. The other choices add unsupported claims about later sales or universal effects (A, D) or posit an unmeasured mechanism (C).
To compare two fertilizers, researchers randomly assigned 60 identical tomato plots to receive either Fertilizer A or Fertilizer B. All plots had the same irrigation schedule and sun exposure, and soil tests confirmed no initial differences across groups. Over eight weeks, the A plots produced, on average, 12 percent more tomatoes by weight than the B plots. The pre-registered analysis reported a statistically significant difference, and field notes recorded no pest outbreaks or equipment failures affecting one group more than the other. Because fertilizer type was the only planned difference between groups, the team attributed the yield gap to that difference rather than to chance or plot conditions. Thus, within the confines of this experiment, the higher yields observed in the A group are best explained by _______.
Which choice most logically completes the text?
tomatoes being inherently more robust this season
the A plots receiving more sunlight
farmers' prior preference for brand A
the causal effect of using Fertilizer A rather than Fertilizer B
Explanation
Random assignment and controlled conditions indicate the fertilizer difference caused the yield difference. Seasonal robustness, sunlight differences, and farmer preferences are unsupported by the study design.
Before assigning grades, a professor told students that only essays demonstrating all three of the following would receive an A: a clear thesis, well-integrated evidence, and original analysis. After grading the first batch, the professor reported that every A paper had all three features and that no paper lacking any one of the three received an A. The rubric had no other criteria for A-level work, and the professor applied it consistently across the section. Because the professor's stated policy matched the observed outcomes, it is possible to infer a precise rule from this batch about what was required and sufficient for an A under this rubric. Therefore, for these essays, it must be true that _______.
Which choice most logically completes the text?
any essay missing even one of the three listed features could not have earned an A
all future essays in the course will earn an A if they include the three features
essays earned A grades because they were written by the highest-GPA students
the rubric should be adopted by the entire department
Explanation
The batch shows that the three features were necessary and sufficient for an A in this context. Predicting future outcomes, attributing grades to GPAs, or prescribing policy are unsupported.
Participants in a workplace sleep program were surveyed three months after enrolling. Among those who completed all eight sessions, 90 percent reported sleeping better than before the program; among those who quit after two or fewer sessions, 10 percent reported such improvement. The two groups did not differ in age, job type, or baseline sleep quality, and no other wellness initiatives were available during the study window. The survey measured only self-reported sleep improvement and completion status; it did not ask about changes in workload or family obligations. On the basis of the available data, the analysts cautioned against claiming that the program improves sleep for everyone. Still, the results show a clear pattern: in this sample, _______.
Which choice most logically completes the text?
completing the program reduced workload, which in turn improved sleep
any worker who completes the program will sleep better
completers were more likely to report better sleep than noncompleters
people who slept better were more likely to complete the program
Explanation
The reported percentages show higher improvement rates among completers than noncompleters. Claims about workload or reverse causation are unsupported, and universal improvement overgeneralizes the findings.
A randomized study assigned ninth graders either to 20 minutes of daily silent reading or to 20 minutes of guided reading with immediate teacher feedback. After eight weeks, the guided-reading group showed statistically significant gains on a standardized comprehension test; the silent-reading group did not improve relative to baseline, and the two groups differed at posttest. Assignment was random, and both groups used the same texts, so the only systematic difference was the presence of feedback. Therefore, within this study, _______.
Which choice most logically completes the text?
students who received guided reading outperformed those who did silent reading on the comprehension measure.
silent reading harms comprehension for all ninth graders.
students with higher initial comprehension chose the guided-reading condition.
teacher feedback makes students enjoy reading more.
Explanation
Random assignment and identical texts isolate feedback as the key difference, and the guided-reading group scored higher. B overgeneralizes beyond the study, C contradicts random assignment (reversing cause), and D is unrelated to the evidence.
At the Rivera Art Supply warehouse, every box in the marker shipment contains markers of a single color only. Company policy states that any box containing red markers is stamped with a large 'R', while boxes containing any other color are left unstamped. The shipment received this morning includes three unstamped boxes pulled from the same pallet. Warehouse staff have verified that the stamps, when present, are always legible and cannot be rubbed off in transit. Given these conditions, _______.
Which choice most logically completes the text?
the unstamped boxes all contain the same non-red color.
workers failed to stamp several red boxes earlier this morning.
unstamped boxes across all shipments always hold blue markers.
none of the three unstamped boxes contains red markers.
Explanation
Only red boxes are stamped, and stamps cannot be lost in transit, so unstamped boxes are not red. A and C assert specifics not supported, and B speculates an error without evidence (non sequitur).
Field biologists studying the Great Basin spadefoot have established that the species initiates breeding only when temporary pools form and soil moisture exceeds a measured threshold. At one monitored site this spring, sensors show soil moisture has remained below that threshold, and no temporary pools have formed. Across these observations, spadefoots at this site have never bred in seasons when the threshold was not met. The breeding window for this population is limited to late spring. Therefore, barring an abrupt change in conditions before the window closes, _______.
Which choice most logically completes the text?
Predation on adult spadefoots will increase this year.
Breeding will not occur at that site this season.
Spadefoots can never breed successfully in dry regions anywhere.
Because the toads did not breed, soil moisture remained below the threshold.
Explanation
Breeding requires moisture above the threshold, which has not been reached, so breeding will not occur this season at that site. A and D are unrelated or reverse cause and effect, and C overgeneralizes beyond the site and season described.
In a semester-long study at Jefferson High, 120 ninth-graders were offered after-school algebra tutoring. Students chose whether to attend, but researchers matched frequent attendees with nonattendees on baseline grades and prior test scores. Teachers reported no changes to grading policies or curriculum during the study, and the school did not introduce any other academic support programs. By semester's end, students who had logged eight or more sessions increased their unit test averages by six points relative to matched peers who attended none. Attendance logs were verified by scan-ins and tutor notes. Given that the biggest shift during the period was participation in this tutoring, the results indicate that _______.
Which choice most logically completes the text?
students' long-term GPAs will rise because of the tutoring.
students improved before attending, which motivated them to sign up.
algebra tutoring is effective for all students in every subject.
higher attendance at the tutoring coincided with larger gains in unit test averages.
Explanation
The data show a positive association between attendance and gains, so D fits. A is an unsupported projection, B reverses the timeline, and C overgeneralizes beyond the study.