Friday, March 27, 2015

Numbers Do Not Add Up

Sometimes people should read what they write. I do, at times, and that is why I am wont to change what I may not add up. But if you are in the NY Times it seems to me that you get away with almost anything. Just look at the number of corrections to the on line stories.

Today in the Times I read a piece which I think spoke of scientists, and most likely engineers too, as well as physicians and surgeons, can get insight by looking at something differently. Wow, that is big news! As if what we have been done for two and a half millennium has been something different. But this statement really rang a bell:

In a recent experiment at the University of Virginia, researchers used a perceptual-learning module to train medical students about gallbladder removal. In the past, doctors removed gallbladders by making a long cut in the abdomen and performing open surgery. But since the 1980s many doctors have been doing the surgery by making tiny incisions and threading a slender tube called a laparoscope into the abdominal cavity. The scope is equipped with a tiny camera, and the surgeon must navigate through the cavity based on the images the scope transmits. All sorts of injuries can occur if the doctor misreads those images, and it usually takes hundreds of observed surgeries to master the skill. Half the students practiced on a computer module that showed short videos from real surgeries and had to decide quickly which stage of the surgery was pictured. The other half — the control group — studied the same videos as they pleased, rewinding if they wanted. The practice session lasted about 30 minutes. On a final exam testing their knowledge of the procedure, the perceptual-learning group trounced their equally experienced peers, scoring four times higher. Their instincts were much sharper.

Now slowly reread the last sentence. These are erstwhile surgeons removing a simple gallbladder via a scope procedure. Those that had this so-called perceptual technique score 4 time higher than the others. Now assume they all scored 100%. That means the regular docs got 25%! You want a surgeon who scored 25%, are you kidding me. Worse, there is zero chance the top group got all 100% most likely 80% average. That means the characters in the regular learning mode got 20%. But wait! We have no idea how badly the top group did, only that the others got only 25% of what they got!

Can we really believe this, does it make logical sense, does the "pattern" make sense? Not really. Perhaps they should go back and check the numbers, or make certain than none of them ever practice least on my gallbladder!