I am currently reading the book – The Black swan by N N Taleb. This is a great book on low probability, high impact events which are termed as black swans.
I am still in the middle of this book. One key point which I came across is ‘confirmation bias’ on which the author has devoted a complete chapter.
The basic idea behind confirmation bias is that once we make a decision, we tend to look for evidence to confirm it. As a result we tend to ignore any negative information which could refute our decision. As a corollary to this concept, any additional information is of no use as it would only re-inforce the decision and not add any more value to the decision making process.
Like others, I am equally susceptible to this bias. My approach to reduce its impact is to write a single page thesis on an investment idea and sometimes post it on my blog. I try to gather negative information and also prefer to get negative feedback on my idea. That helps me in wieghing all negative information and arrive at a better decision (hopefully).
I am not sure if I have been entirely successfull in it, but I have rejected a few ideas after selecting them, once I was pointed out some key information (which I had missed out). In a few other cases, the negative information, which I had missed earlier resulted in reducing my estimate of intrinsic value for the stock – for ex: I missed the impact of liabilities in the case of VST. As a result I ended up taking a smaller position