Question 101·Hard·Inferences
In an assessment of a new employee incentive program, researchers compared the productivity of two factories. The factory that implemented the program had also recently upgraded its machinery, whereas the comparison factory had not. Attributing all observed productivity gains to the incentive program, the researchers concluded that the program was solely responsible for the improvement. The conclusions of the assessment, therefore, ______
Which choice most logically completes the text?
For “complete the text” questions that test logical reasoning, first paraphrase the sentence up to the blank and identify what the author is doing—describing a flaw, adding a consequence, giving an example, etc. Look for mismatches between evidence and conclusion, especially when you see strong words like “solely,” “prove,” or “demonstrate,” which often signal an overreach. Predict the type of statement that should come next (for example, a criticism that the study mixes two variables), then eliminate choices that introduce new topics, go beyond the given information, or make absolute claims not supported by the passage. Finally, choose the option that directly matches your prediction and stays tightly tied to what is actually stated.
Hints
Track all the differences between the two factories
List exactly what changed at each factory. Did only the incentive program change, or did something else change too?
Question the researchers’ conclusion
The researchers concluded that the program was "solely" responsible for the improvement. Ask yourself: based on the description, is there any other plausible cause for the productivity gains?
Predict the type of criticism
Before looking at the choices, decide: should the blank describe a strength of the study, a limitation of how widely it applies, or a flaw in how the cause of the gains was identified?
Step-by-step Explanation
Restate what the study actually did
First, summarize the setup in your own words:
- Factory 1: implemented the new incentive program AND upgraded its machinery.
- Factory 2 (comparison): did NOT implement the program and did NOT upgrade its machinery. Then the researchers saw higher productivity and gave all the credit to the incentive program.
Identify the logical problem
Ask: Can we be sure the incentive program alone caused the productivity gains?
- No, because two things changed at once in Factory 1: incentives and machinery.
- The new machinery could be partly or fully responsible for the improvement. This means the study has a confounding factor: the machinery upgrade is mixed together with the incentive program.
Predict the kind of criticism that should complete the sentence
The sentence setup (“Attributing all observed productivity gains to the incentive program … concluded that the program was solely responsible … Therefore, the conclusions of the assessment …”) is clearly leading to a criticism. That criticism should say something like:
- The conclusions might be flawed or overstated
- Because they fail to separate the effects of the incentive program from the effects of the machinery upgrade.
Match the predicted criticism to the choices
Now compare each answer choice to that predicted criticism:
- One choice says the conclusions may exaggerate how effective the program is because the researchers did not separate the impact of the incentives from the impact of the new machinery. This directly matches the flaw you identified and is therefore the best completion.
- The other choices shift the focus to generalizability (two factories), incorrectly blame the machinery-upgrade conclusion (even though the researchers credited the program), or raise an unsupported concern about the factories’ starting productivity. So the correct answer is: "may overstate the program's effectiveness because they do not distinguish between the effects of the incentives and those of the new machinery."