SAT — inference

The inference question on the SAT takes its own shape: a short passage stops in the middle of its last sentence, and four candidate completions follow. The task is not to decide what is true but to decide what follows, which are different things — and most wrong answers are picked because they are true, or would be true, rather than because the writer has given any grounds for them. These ten questions use that format directly, with passages drawn from the physical sciences, biology, the social sciences, history and the arts.

Two habits decide this question type, and the bank is built around both. The first is keeping the hedge. When a researcher observes one species on one mountainside flowering late in the years the snow lingered, what follows is that snowpack duration may influence the timing — not that the plant requires a late snowpack, not that it will never flower after an early melt, and not that every alpine plant behaves this way. Several keyed completions here say "may be one factor" for exactly this reason, and a reader who finds that unsatisfying is feeling the pull the wrong answers rely on.

The second habit is refusing to supply anything. A biologist reports that a warbler's route shifted only in the years a beetle population collapsed — and the passage also states that beetles are nearly all the bird eats, because without that sentence the conclusion about food would be something the reader brought rather than something the writer gave. Three recurring imports are set as traps across the bank: a motive, as when a narrowing palette is explained by criticism the critic never mentions; a direction of causation, as when broad spectral lines are made to thicken the gas around them; and a comparison with cases never examined. A fourth trap is subtler and catches careful readers: the completion that simply restates a fact already given. It is perfectly true, it contradicts nothing, and it concludes nothing, which in a sentence beginning "this suggests that" makes it wrong.

Each explanation traces the step from the stated facts to the keyed completion and then names what is wrong with each of the other three, describing the completion rather than pointing at its position, so the reasoning survives any reordering of the choices.

Every study, researcher, artist and place in these passages is invented, and no invented finding is attributed to any real organization, journal or university. Nothing is reproduced from any College Board publication, released test, practice test, question bank or scoring guideline, and no copyrighted text is quoted: the passages were written fresh.

Zestly is an independent study tool. It is not affiliated with the College Board, which owns the SAT, and it is not an exam center.

• Complete a passage with the conclusion its own statements support, and no more
• Keep a writer's hedge in the conclusion drawn from a hedged finding
• Refuse a completion that requires knowledge the passage does not supply
• Spot a reversed direction of influence between two things the writer only associated
• Recognize a motive supplied from outside as something no observation could establish
• Reject a generalization from the cases studied to all cases of the kind
• Identify a completion that restates a given fact instead of concluding anything
• Notice a comparison drawn against cases the writer never examined
• Use a stated exception or condition, such as an "only when" clause, to limit the conclusion

Consider this passage. "Historian Clara Minton examined household inventories from the closing decades of the fifteenth century. Printed pamphlets appear in the inventories of towns lying along the newly expanded trade routes, and are almost absent from the inventories of comparable towns away from those routes. This suggests that ______" Which choice most logically completes the writer's statement?