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SAT Evidence That Weakens a Hypothesis

Some evidence questions flip the usual direction and ask what would weaken, undermine, or challenge a hypothesis. The correct answer is not merely unrelated information. It is a result that the hypothesis predicted would not happen, or a result that fits a rival explanation better.

The rule

Weakening evidence shows the relationship the hypothesis predicted failing to appear, or shows another explanation accounting for the same result.

Start by writing out what the hypothesis predicts. If a researcher hypothesizes that a plant grows taller because of increased sunlight, the prediction is that plants with more sunlight grow taller and plants with less do not. Weakening evidence breaks that prediction, for example a finding that plants in shaded areas grew just as tall.

There is a difference between absent evidence and contrary evidence. A choice saying the researcher did not measure soil quality points at a gap in the study. A choice saying plants in poor soil grew slowly regardless of sunlight actively supplies a competing explanation. The second one weakens the hypothesis more directly, and on the SAT the directly contradicting result is nearly always the answer.

The most common wrong answer is a finding that is simply about something else. If the hypothesis is about sunlight and growth, a finding about the flowering season is neither support nor challenge. It reads as substantive because it is specific and scientific sounding, but it leaves the predicted relationship untouched.

The second most common wrong answer supports the hypothesis while looking negative. A finding that growth was slower than the researcher expected still shows more sunlight producing more growth, which is the direction the hypothesis predicts. Check the direction of the relationship rather than reacting to words like failed, less, or did not.

Do the same work in reverse for questions that ask what would support a hypothesis. Strong support matches the hypothesis on the group, the variable, and the direction all three at once. If any of the three is off, the choice is describing a different finding, however true it might be.

The trap

Selecting a choice that raises an unrelated question about the study instead of contradicting the predicted relationship.

Try it

Try one
Real question

Using account books from a manor in fourteenth-century England, historian Edward Oduya compared the size of each year's wheat harvest with the price of wheat at a nearby market over five years. Accounts of this kind were drawn up each autumn by the reeve who ran the estate for its lord, and they record the grain threshed from each field beside the acreage sown, letting a yield per acre be reconstructed centuries later. Prices at the time depended heavily on local supply, since grain was costly to move over long distances. Oduya concluded that poor harvests drove wheat prices up: ______

Wheat Harvests and Prices on One English Manor
YearHarvest (bushels per acre)Price (pence per bushel)
1331116
133298
1333125
1334613
1335107

Which choice most effectively uses data from the table to complete the statement?

Engineers have proposed that adding crushed volcanic ash to cement reduces cracking because the ash keeps reacting for years, slowly filling fine gaps. The idea is old: Roman builders mixed ash from the Bay of Naples into mortar that still stands today. The ash supplies silica that reacts with the lime cement releases. Skeptics counter that any improvement simply reflects the lower water content of ash mixtures. Materials researcher Lucía Terán set out to separate the two, casting ninety prisms, curing them in water baths, and measuring the pore space in each one.

Which finding, if true, would most strongly support the continuing-reaction explanation over the water-content explanation?

  • A) Ash mixtures were stronger than ordinary mixtures after one day.
  • B) Ash mixtures required less water to reach a workable consistency.
  • C) Ash mixtures and ordinary mixtures made with identical water content performed alike at one month, but the ash mixtures had far fewer fine gaps at two years. ✓
  • D) Ash mixtures cracked less than ordinary mixtures at every age tested.

Why: The question asks for evidence favoring the continuing reaction over lower water content, so water has to be matched and the benefit has to arrive late, which mixtures alike at one month and far fewer fine gaps at two years give. One finding is about the first day: Ash mixtures were stronger than ordinary mixtures after one day. An advantage within a day is far too early for a reaction said to run for years, and lower water content would produce it. Another states the skeptics' premise: Ash mixtures required less water to reach a workable consistency. Needing less water to reach workability is the rival explanation, not evidence against it. The last leaves water content uncontrolled: Ash mixtures cracked less than ordinary mixtures at every age tested. Less cracking at every age, including the earliest, is what the water explanation predicts too.

Practice more of these free

Questions students ask

Does pointing out a flaw in the study count as weakening the hypothesis?

Only weakly, and the SAT usually offers a better option. A flaw suggests the evidence is unreliable, while a contrary result shows the prediction actually failing. When both appear among the choices, the contrary result is the stronger answer.

How do I keep support and weaken questions straight?

Underline the verb in the question stem before reading the choices. Support means the same direction as the prediction, weaken means the opposite. Students who miss these often solved the question correctly and then answered the version they expected rather than the one asked.

Guides that cover this

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