In other words, asking people for a best guess or an optimistic prediction results in a biased prediction that is almost always earlier than a real delivery date. On the other hand, while the pessimistic question is not more accurate (it has the same absolute error margins), it is unbiased. The reality is that the study says that people asked for a pessimistic question were equally likely to over-estimate their deadline as they were to under-estimate it. If you don’t think a question that gives you a distribution centered on the right answer is useful, I’m not sure what to tell you.
It’s interesting that the median of the pessimistic expectations is about equal to the median of the actual results. The mean clearly wasn’t, as that discrepancy was literally the point of citing this statistic in the OP:
in a classic experiment, 37 psychology students were asked to estimate how long it would take them to finish their senior theses “if everything went as poorly as it possibly could,” and they still underestimated the time it would take, as a group (the average prediction was 48.6 days, and the average actual completion time was 55.5 days).
So the estimates were biased, but not median-biased (at least that’s what Wikipedia appears to say the terminology is). Less biased than other estimates, though. Of course this assumes we’re taking the answer to “how long would it take if everything went as poorly as it possibly could” and interpreting it as the answer to “how long will it actually take”, and if students were actually asked after the fact if everything went as poorly as it possibly could, I predict they would mostly say no. And treating the text “if everything went as poorly as it possibly could” as if it wasn’t even there is clearly wrong too, because they gave a different (more biased towards optimism) answer if it was omitted.
This specific question seems kind of hard to make use of from a first-person perspective. But I guess maybe as a third party one could ask for worst-possible estimates and then treat them as median-unbiased estimators of what will actually happen? Though I also don’t know if the median-unbiasedness is a happy accident. (It’s not just a happy accident, there’s something there, but I don’t know whether it would generalize to non-academic projects, projects executed by 3rd parties rather than oneself, money rather than time estimates, etc.)
I do still also think there’s a question of how motivated the students were to give accurate answers, although I’m not claiming that if properly motivated they would re-invent Murphyjitsu / the pre-mortem / etc. from whole cloth; they’d probably still need to already know about some technique like that and believe it could help get more accurate answers. But even if a technique like that is an available action, it sounds like a lot of work, only worth doing if the output has a lot of value (e.g. if one suspects a substantial chance of not finishing the thesis before it’s due, one might wish to figure out why so one could actively address some of the reasons).
It’s interesting that the median of the pessimistic expectations is about equal to the median of the actual results. The mean clearly wasn’t, as that discrepancy was literally the point of citing this statistic in the OP:
So the estimates were biased, but not median-biased (at least that’s what Wikipedia appears to say the terminology is). Less biased than other estimates, though. Of course this assumes we’re taking the answer to “how long would it take if everything went as poorly as it possibly could” and interpreting it as the answer to “how long will it actually take”, and if students were actually asked after the fact if everything went as poorly as it possibly could, I predict they would mostly say no. And treating the text “if everything went as poorly as it possibly could” as if it wasn’t even there is clearly wrong too, because they gave a different (more biased towards optimism) answer if it was omitted.
This specific question seems kind of hard to make use of from a first-person perspective. But I guess maybe as a third party one could ask for worst-possible estimates and then treat them as median-unbiased estimators of what will actually happen? Though I also don’t know if the median-unbiasedness is a happy accident. (It’s not just a happy accident, there’s something there, but I don’t know whether it would generalize to non-academic projects, projects executed by 3rd parties rather than oneself, money rather than time estimates, etc.)
I do still also think there’s a question of how motivated the students were to give accurate answers, although I’m not claiming that if properly motivated they would re-invent Murphyjitsu / the pre-mortem / etc. from whole cloth; they’d probably still need to already know about some technique like that and believe it could help get more accurate answers. But even if a technique like that is an available action, it sounds like a lot of work, only worth doing if the output has a lot of value (e.g. if one suspects a substantial chance of not finishing the thesis before it’s due, one might wish to figure out why so one could actively address some of the reasons).