Correctly measuring the productivity of service workers is complex. Co

Since the question stem refers to "the productivity measure described", let's make sure we understand what that means before analyzing the answer choices.

The passage states that postal workers "are often said to be more productive if more letters are delivered per postal worker". How is productivity being measured in this phrase? Only by the number of letters delivered (the output) per postal worker.

By asking, "But is this really true?", the author questions whether productivity of service workers can be measured solely by output per worker (or number of letters delivered per postal worker, in this case). This is the author's main objection. The author elaborates by asking, "What if more letters are lost or delayed per worker at the same time that more are delivered?" In that scenario, the output is increased (more letters are delivered) but the overall quality of the services performed is sacrificed, since more letters are lost or delayed.

So what's the question asking us for? Well, the author's objection (about whether productivity of service workers can be measured solely by output per worker) is "based on doubts about the truth of" one of the answer choices. Let's take them one at a time.


The author questions whether productivity can be measured solely by output and simply uses postal workers as an example; the author does not question whether postal workers are in fact representative of service workers in general. So (A) is gone.


By saying that postal workers "are often said to be more productive if more letters are delivered per postal worker", the author gives an example of using output (number of letters delivered) to measure productivity. The author does NOT imply that this measure of productivity is flawed because delivery of letters is not the primary activity of the postal service. Instead, the author implies that this measure is flawed because it doesn't address the quality of the services (i.e., lost or delayed letters). So we can cross out (B), too.


The author's objection relates to how productivity is measured, not to whether it is ascribed to categories of workers or to individuals. Although the author does discuss a category of workers (postal workers), the author doesn't address whether productivity should be measured at the level of groups or individuals. We can eliminate (C).


Remember that the author's main doubt is whether productivity can be measured solely by output per worker (i.e., number of letters delivered per postal worker, in this example). In the example about postal workers, the output per worker is increased, but quality of service declines. So in the passage, the author is clearly doubting whether quality can be appropriately ignored in computing productivity. So (D) looks good!


The author does not imply that the number of letters is not relevant to measuring the productivity of postal workers; rather, the author objects to whether productivity can be measured by output alone. The author implies that other factors, such as quality of services rendered, should be considered in addition to output when measuring productivity. So we can get rid of (E).

And that leaves us with (D).