A Case of Elementary Decision Trees "The scene is the drawing room at 221b Baker Street...
'Watson, I must explain the facts to you. This slump in the stock market since the outbreak of the Boer War has left me penniless. I must seek my fortune.' 'Holmes, that's deadful... but perhaps this letter from Inspector Lestrade of Scotland Yard can help. He says that Moriarty's evil influence is spreading. An insurance company is offering 100,000 guineas to anyone that can catch him, and 50,000 guineas to anyone that leads the police to him. By jove, they're even offering 10,000 guineas for genuine information on him, even if the bunglers at Scotland Yard fail to apprehend him.' 'Splendid, dear Watson, for my brother Mycroft has told me that Moriarty has travelled to Switzerland - near the Reichenbach Falls.' 'Then let us travel on the next boat train. It'll be my privilege to pay for us both.' 'Hold on a moment, Watson. If we visit Reichenbach, I would estimate our chances of finding him at no higher than 60%. If we do, we must decide whether to tackle him or bring in the police. On o ur own against Moriarty's thugs we have no better than a 40% chance of getting our man. The police have probably got a 60/40 chance of success.' 'Perhaps we should tell the police right away, and let them go to Switzerland, then, Holmes' 'Hm... those idlers will take so long getting there that I suspect they've no better than a 3 in 10 chance of finding him and arresting him... How much do you suppose the expedition will cost us, Watson?' 'About 200 guineas, I'd say, Holmes' ![]() One of the first things you may be wondering is what the hell is going on here. Surely Sherlock Holmes was around before the time of decision trees, perhaps you don't even know what a decision tree is. If you don't even know who Holmes himself was, he was a bad ass detective & crime-solving motherfucker much like John Shaft from Shaft and the guy with the beard from Diagnosis Murder. He also smoked a pipe like the one in the picture above. The purpose of this article is not really to talk about decision trees, or anything else business related but rather to just point out the obvious flaws in Holme's decision to use a tree to make his decisions. This is what the tree would be like:
It's quite self explanatory. It contains all the supposed possible outcomes for the sitation described at the top. According to the tree, the best option for Holmes and Watson (which will give them the highest estimated monetary value) is to go to switzerland, find moriarty and try to tackle him. But it clearly doesn't take into account the following:
Article Written by Jay |