A study question tests whether a comparison supports the researchers' claim about a cause. Read how the groups were set up, and list what changed between them along with what each showed. Then ask whether more than one change could explain the result, because a comparison can't separate causes that always occur together. Check the strength of the researchers' claim against what the study can show. Wrong choices often treat a possible explanation as a proven one.
Hints
- Hint 1
Read the sentence about the factory that implemented the program, and list every way the factories differed.
- Hint 2
Can this comparison show how much each change contributed to the productivity gains?
- Hint 3
Test the researchers' certainty. What would they need to rule out to call the incentive program “solely responsible”?
Step-by-step
Separate the possible causes
Step 1Map the factories
The researchers compared the productivity of two factories, so let's list what separated them as we judge their conclusion. Was the incentive program the only difference? The program factory had upgraded its machinery too, while the comparison factory had not. Both the incentives and the machinery changed between the factories.
- Step 2
Ask what the comparison can show
Can we tell how much each change contributed to the gains? The factory that implemented the program had also recently upgraded its machinery, so the increase could come from the incentives, the machinery, or both. A comparison factory without either change doesn't separate those possibilities. To test the incentives alone, the researchers would need factories that differed in the program but not in their machinery upgrades. The study can't divide the credit between the two possible causes.
- Step 3
Test the researchers' claim
The researchers call the program solely responsible for the improvement. How strong is that claim? It gives the incentives all the credit for the gain, while the machinery could have contributed too. Only two factories focuses on which factories the result applies to. Similar productivity levels before the program claims the researchers failed to show something, but the text doesn't say that. The study doesn't support giving the program all the credit.
- Step 4
Match a cautious criticism
Which choice questions the words solely responsible without deciding that the program did nothing? May overstate the program's effectiveness questions how much credit the incentives receive, and do not distinguish names why that credit is uncertain. It leaves open how much the program helped rather than assigning the gains to either cause. Choice B.