Evaluate-the-Argument Questions on the LSAT: Test What the Missing Information Changes

By AccessPrep Editorial · November 11, 2026

An evaluate question asks which missing information would be most useful for judging the support for a conclusion. Identify the conclusion, locate the gap, and test plausible answers to each serious contender. Choose the information that most directly distinguishes a stronger case from a weaker one. You do not need proof, and you should not reject relevant evidence merely because it leaves other explanations possible.

The examples and exercises below are original AccessPrep teaching materials, not official LSAC questions. All people, businesses and events are fictional. The method is a study aid, not a validated score-improvement formula.

Jump to: Five-step check · Traffic example · Relevance and proof · Worksheet · Fresh practice · Review errors

What you are trying to learn

This lesson is for readers who recognize an evaluate stem but choose whatever sounds connected to the subject. The aim is more precise: explain how an answer would change the relationship between the stated evidence and the conclusion.

LSAC’s Logical Reasoning overview identifies relevance and the effect of additional evidence as reasoning skills the test assesses. Our procedure below is a way to practice those skills, not an LSAC rule about the form every correct choice must take.

A useful question need not have a simple yes-or-no answer. It might ask for a quantity, a comparison, or an explanation. Even when it does ask whether something happened, one answer may undermine the argument while the other merely removes that particular objection. Do not manufacture equal-and-opposite effects to fit a formula.

The five-step check

1. Write the conclusion exactly. A claim about fewer collisions is different from a claim about a lower collision rate per car. A prediction about purchasing costs is different from a prediction about total profit.

2. Separate the evidence from the gap. Name what is stated, then what still needs support. A causal gap might concern an alternative cause, the direction of causation, a measurement change, or a comparison that was not controlled.

3. Read the choice literally. If it asks whether traffic changed, “yes” includes both an increase and a decrease. You cannot silently translate it into “did traffic fall?” If it asks how much traffic changed, test concrete values instead.

4. Try two informative answers consistent with the premises. Describe what each answer changes. “Stronger,” “weaker,” “little change,” and “depends on the amount” are all possible observations. Explain the connection in a sentence.

5. Compare the contenders. Prefer the question that most directly tests the disputed inference with the fewest extra assumptions. A weaker contender can still be relevant. “Does not prove the conclusion” is not a sufficient reason to eliminate it.

Before checking an explanation, preserve your original choice and your reasoning. Then write the correction separately. Otherwise the explanation can replace your memory of what went wrong.

Worked question: collisions and traffic volume

Original fictional practice item.

The city replaced Maple Avenue’s streetlights with brighter ones. Recorded nighttime collisions fell from 90 in the year before installation to 60 in the year after installation. The transportation office concludes that the brighter lights caused the decline.

Which question would be most useful in evaluating that conclusion?

(A) How did the number of nighttime vehicle trips on Maple Avenue change between the two years?

(B) Were the streetlights purchased in one order or in several orders, with the same installation date either way?

(C) Did any nighttime collisions occur on Maple Avenue after installation?

(D) Did the electricity bill for the streetlights increase after installation?

(E) Was the office’s announcement about the lights printed in color or in black and white?

Record your choice and two possible answers before continuing.

Answer and explanation

Answer: A. The office uses a fall in the number of collisions to support a causal explanation. Fewer opportunities for collisions are a competing explanation. Traffic volume bears directly on that possibility.

For illustration, suppose there were 900,000 nighttime vehicle trips in the first year. That is 10 collisions per 100,000 trips. Consider three possible answers about the second year:

These are hypothetical answers, not additional facts in the stimulus. None settles whether the lights had some effect. For example, road design, weather, vehicle mix or reporting could also change. The question is useful because its answer changes the interpretation of the evidence, not because it proves a single cause.

B: purchasing administration. Under the choice’s fixed installation date, the number of purchase orders does not itself address traffic exposure, lighting effectiveness or collision measurement. To connect it to the conclusion you would have to add facts not supplied.

C: already answered. The stimulus gives 60 collisions after installation, so the answer is yes. “No collisions” contradicts a stated premise. Do not treat an impossible answer as a legitimate alternative outcome.

D: a different outcome. Electricity spending does not directly test the stated collision explanation. A higher bill might matter in a cost-benefit argument, but this conclusion is not about whether the policy was worth its price.

E: announcement format. The printing choice does not bear on the traffic or collision evidence without inventing a further story about behavior.

A single hypothetical answer that would affect support gives you a reason to examine a choice. Testing a second plausible answer reveals what the first result depends on. Then compare both choices against the exact question, as recommended in LSAC’s Logical Reasoning approach.

The tempting mistake: requiring proof

Suppose another choice asked whether comparable streets in other cities experienced fewer collisions after getting the same lights. That could matter. A well-matched comparison would be more informative than a poorly matched one. Differences in traffic, road layout and measurement could limit what you infer, but they would not make all outside evidence irrelevant.

A weak explanation says, “Other cities cannot prove what caused Maple Avenue’s decline, so that choice does nothing.” The repair is: “The comparison may support a lighting effect; I need to assess its similarity and compare its usefulness with the direct traffic-volume check.” Relevance and conclusiveness are different standards.

Try comparing these two versions of the outside-streets question. “Did another city install the same model?” tells you only that you might have a comparison available. “Did comparable unlit streets in the same city see the same drop in collisions per trip over those years?” could directly challenge the lighting inference. A similar drop would raise the possibility of a change common to both groups. A drop confined to Maple Avenue would make that shared explanation less persuasive. Comparability still matters, including traffic mix and how collisions were recorded. This second question would deserve serious consideration if it appeared among the choices.

Likewise, asking whether a policy was introduced after an unusually bad year can raise a real concern about whether that year was atypical. Do not label every question about the decision to introduce a policy irrelevant merely because it concerns events before implementation.

Two answer choices can therefore deserve attention. If both seem useful, return to their exact wording, the precise conclusion, and the amount of unstated information your explanation requires. Do not force one to become irrelevant simply because the answer key selects the other.

Copy this evidence worksheet

Use this record for each of your final two contenders:

Completed Maple Avenue record: Conclusion: the lights caused the count to fall. Evidence: 90 collisions before, 60 after. Gap: exposure may have changed. Choice A asks for the change in trips. Unchanged trips leave fewer trips unavailable as an explanation; a one-third fall in trips leaves the collision rate unchanged. A is the strongest choice here because it tests the count-to-cause inference directly. The repair is to distinguish a count from a rate and to test actual values instead of rewriting the question.

Fresh practice: reusable cups

Original fictional practice item. Solve before opening the separate answer key.

A bakery serves 10,000 coffees per month and expects that volume to remain constant. A disposable cup costs $0.20. A reusable cup costs $2 to buy and $0.05 to wash after each use. All other costs would remain unchanged, and deposits would neither add to nor subtract from the bakery’s net costs. The owner concludes that switching to reusable cups would lower the long-run average cup purchase and washing cost per month.

Which question would be most useful in evaluating the owner’s prediction?

(A) What is the average number of uses a reusable cup would provide before it must be replaced?

(B) How much would the bakery spend to buy its initial reusable-cup inventory?

(C) Was the reusable-cup supplier founded before the bakery opened?

(D) Would the owner announce the change on a Monday or a Tuesday?

(E) Does a disposable cup currently cost $0.20?

Write a choice, the cost relationship it tests, and two possible numerical answers. The practice packet contains the question-only exercises, editable worksheet and a separate answer key. Open the question file first and record your reasoning before consulting the key.

Check the scope before you judge an answer

The bakery question specifies constant sales volume, unchanged other costs, and neutral deposits. Those details are necessary to isolate the instructional problem. Without them, customer preferences might affect sales, a deposit might affect return rates or revenue, and extra washing labor might offset savings. You should not automatically dismiss those matters in an argument that leaves them open.

A claim about monthly costs also needs a time frame. The question concerns long-run average cost, including replacement purchases. A large first order could reflect a high price per cup or simply a large initial stock. The question fixes the unit price, and a larger stock by itself says little about eventual cost per serving. If the claim concerned first-month cash flow, the initial purchase would matter directly. It does not claim that buying an initial inventory saves cash in the first month. Always check whether a proposed answer addresses the conclusion actually written.

For a quantity question, “high” and “low” are often too vague. Ask where the answer starts to change the comparison. You do not need advanced mathematics: write the two quantities being compared, use numbers that plainly fall on either side, and explain what the difference means. If no threshold can be calculated from the stated facts, say what additional information would be needed instead of inventing it.

Keep the question types separate

A strengthen choice supplies information that improves support. A weaken choice supplies information that reduces support. An evaluate choice identifies information whose answer helps judge support. A necessary-assumption choice states something the reasoning requires. These tasks can concern the same gap, but the stem determines what the answer must accomplish.

“Traffic fell by one-third” supplies a potential weakening fact. “How much did traffic change?” asks for information that could be informative in several directions. Do not answer the latter as if the task were to select a fact already known to damage the argument.

Nor should you demand certainty. If unchanged traffic removes one rival explanation, other rivals can remain. If a large traffic decline makes the office’s evidence less convincing, a lighting effect can still be possible. Support comes in degrees.

Review errors and choose the next practice step

Classify the error you can actually document:

• Changed the question: you tested a narrower question than the answer choice asked. Copy the choice exactly before testing it again.

• Contradicted a premise: one hypothetical answer was impossible given the stimulus. List the fixed facts first.

• Confused relevance with proof: you rejected information because it did not settle the issue. Write the smaller effect it could have.

• Changed the conclusion: you assessed cost when the conclusion concerned safety, or profit when it concerned a particular expense. Underline the conclusion’s outcome and time frame.

• Added a story: your explanation needed several unsupported events. Compare a more direct contender.

Use the same log on a fresh official question obtained through LSAC’s official practice resources. Keep your own answer and reasoning separate from the key. A familiar item can demonstrate the method but cannot show whether you can transfer it.

As a practical study rule, attempt three fresh questions across two sessions. If you can explain the support change and the competing choice on each, return to mixed practice and watch for recurrence. If not, practice the specific error above before doing more full questions. This is a suggested allocation of study time, not a validated mastery threshold or a prediction of your score. If you lack fresh evaluate questions, do not reclassify memorized answers as new evidence.

Put the method into your next review

Free next step: complete the worksheet for one missed question, then try the bakery item without its key. Bring the corrected reasoning into your next mixed practice session. The blind-review guide helps keep independent reasoning separate from explanations; the weekly review guide helps turn the result into a study task.

If you want feedback on your approach, discuss your study plan with AccessPrep. Bring a missed question and the two possible answers you tested.