Survivorship Bias and Godmen

I am in the middle of Fooled by Randomness by Nassim Nicholas Taleb. He talks about how we tend to draw the wrong conclusions about mutual fund performance by looking at the historical performance of today’s mutual funds. We don’t include the performance of all the funds that were closed or merged, generally on account of poor performance, because they aren’t around. This is called Survivorship Bias.

I find that Survivorship Bias is very useful in explaining the Godman phenomenon as well.

Let’s say you are diagnosed with an untreatable disease that has a survival rate of 10%. You make a trip to a godman. He blesses you. Two weeks later you die. The godman carries on blessing other people. But you are dead and unable to come back and ask him for an explanation for why his blessing didn’t work.

Let’s say that you are one of the lucky 10% who survive. You are so grateful to the godman that you become a devout follower. Not just that – you become an evangelist. You speak of his greatness to anyone who would care to listen. You wear conspicuous marks of your devotion on yourself – a ring, a mala – and put up his images on the walls of your house.

Let’s reduce this down to numbers. From the godman’s perspective, the ‘return’ on his blessing is zero 90% of the times when the person blessed, dies. But 10% of the times the person blessed survives and becomes a devotee and an evangelist. As long he blesses a lot of people, the odds are in his favour. The number of his followers will grow.

This was a very simplified version of reality for which the survivorship bias explains things quite well. But reality can be more complex. For instance, the blessing may be sought by a family member and not the dying person. Or the blessing may be sought for a less morbid reason – say success in a new venture.

Even in these cases you can explain how essentially random post-blessing results can still have positive outcomes for the godman’s following. Human nature makes this possible. People who are disappointed with how things turn out post-blessing may not become devotees but will probably not start advertising the fact that the godman is a fraud. But people who get what they had wished for become evangelists. The outcome for the godman’s following is thus biased towards a positive outcome. Over thousands and thousands of blessings, random events will cause a net increase in the godman’s following. Let’s call this the Evangelism Bias.

The Evangelism Bias explains other (seemingly) less irrational behaviour as well. Homeopathy, for instance. There are no clinical trials that can demonstrate its efficacy. However, it is widely used, especially for chronic diseases. The Evangelism Bias can explain the success of homeopathy but only if there is no other negative effect. Thus it is important that homeopathy produces no side effects and that it is easy to administer (sweet balls of glucose – can’t get any easier). Ayurveda, doesn’t always have this advantage. ‘Go Mootra’ as a treatment for anything is unlikely to get too popular. Chyawanprash, on the other hand, is popular.

Before you go and put me down as a rationalist preaching from Mt. Reason, I must admit that my family and I have often resorted to Ayurveda and Homeopathy when modern medicine hasn’t given us the answers. No godmen yet, but there’s still time for that. Taleb, in his book, contends that human beings aren’t wired to think in terms of probability and random events and carry many biases within themselves. That may be so, but when you are facing a chronic or life-threatening illness, and the doctors have nothing more to offer, you can’t just sit there. You feel the need to do something. And to have faith in something, anything.

Some of these ideas were developed in conversation with Gaurav Rastogi.


  1. Shashi says:

    I am reading the same book, with “The Black Swan” in the pipeline!

    BTW, his name is Nassim Taleb.


  2. Gopal says:

    Nope..i dont think this godman argument “bias” is entirely true..the relatives/friends will always remember that the godman blessing did not work..and word of mouth publicity in these kind of things spread fast..
    I guess you have heard about doctors who are branded as “unlucky” based on 1 or 2 cases in which the patient died..(due to some serious complications and not due to wrong diagnosis or wrong treatment..) and people tend to avoid those doctors. I guess there are lot of other factors in play here and cannot be theorized so simply..


  3. Krishna says:

    You seem to analyse rickshaw fares, BCCI and now the Godman phenomenon – what’s up next? 🙂

    But where does that bias comes from? I don’t know much about failed Godmen. They vanish without a trace. But I have often thought about what makes them a hit, so much that the wealthy disciples gift them rows of Rolls Royce cars and priced real estate. That does not just count Rock stars in search of a mythical Nirvana; it adds in a fair bit of intelligentsia, some of them even sworn agnostics till then.

    I manage to get a glimpse of two realms – One being, the Godman (say *GM-1.0*) offers a sanctuary where the people have no sense of fear or limitation, where they aren’t pulled down by pettiness, where they are just naturally generous and enthused about life, and engaged in making the world a better place. Most GM-1.0 are naturally good everyday people, living their lives with joy and humor, stopping to help someone with a flat tire, helping a short person reach the can of food on the top shelf at the supermarket – without being asked – and looking at the world with courage and hope. Slowly they assemble a like minded group and a *cult* forms up. Soon the cult expands, gets influential, donations pour in, builds up a huge corpus and hands it over to a trust to manage. That’s exactly when it gets political – and by extension, out of hand.

    There’s another tribe (say GM-2.0) of Godmen that gets me worried. They materialize sacred ash and gold chains out of thin air, with a wave of his hand and mesmerize his disciples into faith. His brand of faith. These are the realms of expert magicians and artful dodgers. I’ve noticed the folks that run to this tribe are the ones whose lives are in chaos and literally didn’t know where to turn. Its simplicity (the visual appeal, more so!) cuts through the disciples’ intellectual arguments very quickly, touching deeper truths that their own fears were masking at that time in their lives. This traps even the staunchest rationalists at a time when so many of them are cynical about providence, yet are vulnerable and constantly searching for ways to reach deeper. GM-2.0 make it seem easy to move beyond one’s own fears, and when (s)he is able to drop their intellectual pretenses and let these sights and sounds (of incantation) in, and in that semi liberated state, something quite wonderful happens. The Godman 2.0 makes it look like it’s his `effect’ and his coterie takes over the PR part. [I think of `Miracle Life Crusade’ here]. They ensure that the disciples don’t ever see it as their state of mind that drove them move beyond their own blocks to see the larger truth. They wouldn’t let you ponder complex theological concepts but just make sure it sparks something important in your heart that compels you to reach for your wallet, or even cheque book. Something that which you confuse with GM-2.0 mediated deliverance.


  4. vinay says:

    Hey Basab,

    Just finished reading his latest book – The Black Swan. It is much better than ‘Fooled by Randomness’. Do read that when you are done with this.



  5. Ram Su says:

    If predictors are owls, believers are fools, this fool-owl bonding goes on & on for ever!


  6. Shefaly says:

    Basab: Interesting post.

    In the academic publishing world especially in the sciences this is the phenomenon of positive publishing or ‘positivity bias’. One rarely comes across papers that negate the hypotheses which they set out testing. Not that this does not happen but such papers do not get past reviewers.

    In social sciences, where the scientific methods of hypothesis structuring and data collection and analysis may be used, hypotheses are often modified as one goes along. This is of course not possible in science.

    This also means that sometimes shaky hypotheses remain inadequately tested – because those chasing academic careers do not wish to appear too radical by taking on challenging tasks – while others get firmer and firmer with more weight of evidence behind them. Often the rare random voices of dissent are cruelly crushed as you may know from the strange case of Dr Arpad Pusztai and the GM potato.

    In real life too, as you say people do not start negative advertising campaigns, people do not wish to stand out as too radical by questioning something that many appear to be swearing by.

    You can test this on your blog by posting something that challenges the views of a majority of your reader population and see the outcome as the discussion veers from the logical to the illogical to the downright sublime territory where your readers start attacking other readers’ views.

    Sounds awful? Well proves your point, does it not? 🙂 Most will not even bother with the risk considering the general received wisdom says otherwise.



  7. Basab says:

    Shashi, good catch. His full name is Nassim Nicholas Taleb. I have made the correction.

    Gopal, your point that bad news travels faster, is true, but in matters of faith (unlike the competence of doctors) skeptics hold back their skepticism. Richard Dawkins in his book “The God Delusion” decries similar behaviour from atheists who tend not to talk about their atheism thus making atheism a meme that is weak at propagation.

    Krishna, I would say that my post was about the type of godmen that you call godman 2.0. Spirituality and a balanced life is an important part of the Indian culture and Hindu religion. There are gurus who preach this and it has a large following amongst rational people who see it as a better way of life.


  8. Basab says:

    Shefaly, you make a very good point – that people hesitate to go against the flow or to express an opinion that goes against the majority view. Let’s call this the “Emperor’s New Clothes Bias”. This however, is not the same as the “Evangelism Bias”. For my godman hypothesis to work, the Evangelism Bias needs to express itself even when the followers of a godman are a micro-community. Otherwise, they will be ‘nipped in the bud’ as it were. Once the godman establishes himself, the ENC bias then might reinforce the Evangelism Bias and help the godman’s meme propagate at a greater speed.


  9. Shefaly says:

    Good points, both.

    Most conversation fodder however does emanate from challenging the ENC bias, I think. 🙂



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