From Wikepedia (yes, it does serve some purpose):

Twain popularized the saying in “Chapters from My Autobiography”, published in the North American Review, No. DCXVIII., July 5, 1907. “Figures often beguile me,” he wrote, “particularly when I have the arranging of them myself; in which case the remark attributed to Disraeli would often apply with justice and force: ‘There are three kinds of lies: lies, damned lies, and statistics.’”[1]

Still, it was absolutly clear from my post that the sentence lead-time bias referred to the example before it and not the one that followed. Honestly, did you really miss what I mean or did your (mis)interpretation of my words was deliberate?

Of course, taking two different sentences out of context and deliberately misenterpreting them is one way to discredit someone you talk with…

If you have an MI, you’d go to cardiologist, and the cardiologist will treat you and maybe prescribe you a drug to prevent another MI. However, it’s not cardiologists but statisticians who evaluated data from studies of this drug and determined that it worked. Since the cardiologist only sees individual cases, he or she cannot determine if the drug works or if his patients’ didn’t have another heart attack because of the drug but for some other reason such as for example lifestyle changes, luck or something else. This determination can be made by experts whose job is to design the studies in a way that would eliminate confounding factors, but also to evaluate the data, correlate the information, adjust for biases. Cardiologists aren’t trained to do it, it’s not their job.

Similarly with studies of screening. Oncologists see individual cases. They see a early case of cancer and they see that the person survives longer. Is it because of early detection or because of lead-time bias? The oncologist wouldn’t know that since this cannot be determined by simply treating individual cases, but an oncologist would love to think that it was because of early detection. Frankly, judging from some of the oncologists’ opinions, some of them cannot even spell lead-time bias… Similarly, is a particular cancer cured because it is detected early or was it detected early because it was slow growing or even not growing at all? Not only oncologists cannot determine it based on individual cases they see, they aren’t exactly objective. Nobody wants to think they harmed someone by treating them unnecessarily, it is much more pleasant to believe they cured the person. But even with all the best intention, only by evaluating large amount of data, analyzing the data for biases, correlating the data can these things be determined. Oncologists aren’t experts in determining if screening save lives or just detects cancers or some combination of this. It’s simply not their job.

Further, oncologists are not statisticians. They are not equipped nor trained to see the big picture. Of course, the big picture is only part of deciding a course of treatment, i.e., individual difference can be determinative, not population averages. However, for recommending global guidelines the big picture is most important–and more important than any practitioner’s puny perspective.

Does anyone else find this line of reasoning absurd? The idea that experts from a field should be excluded from practice guideline decisions is misguided. The only other organization I can think of that adopts this line of reasoning is Congress.