Stereotyping the Heterogenous ...

Do you occasionally come across articles like this one about how (most) MBAs fail at startups?  

I understand that the author, like any human-being navigating an information-rich world, needs to use some generalisations to make his story succinct. Across a population with a defined and unifying underlying trait, you could assume that there will be certain characteristics that are almost universal with the exception of a few outliers. Stereotypes  like "women are better listeners than men" or "Asian people eat more rice than Caucasians" might not be 100% true but at least the population that is being stereotyped does actually share one or more unifying, underlying trait such as gender or race.

The odd thing about stereotyping people who happen to have been to business school is that there is no one unifying trait to define them by. They have different backgrounds, different nationalities and have different aspirations and motivations. Some are good at numbers while others are good at words. Some like to talk a lot and others use words sparingly. One student might be a 26 year old Russian female who ran a media agency while her classmate might be a 40 year old Brazilian man who played professional violin. The only thing they actually really have in common is that they decided to take some time out of their careers to go back to school and study business. I never understood why such a heterogenous group of people are so frequently said to be collectively good at X, succeed at Y or fail at Z.

The statement that the author makes does not confuse me - maybe most MBAs do actually fail at startups? Guy Kawasaki is said to have quipped that the pre-money valuation of a startup = ($1M*n_engineers) - ($500k*n_MBAs). Many people in the start-up world do believe that MBAs do not make good entrepreneurs and they might be right. It just confuses me that a population of people with no real underlying uniform trait are frequently and arbitrarily bundled together.

I am on the lookout for other arbitrary groupings of heterogenous populations so please do share. I  look forward to you sharing articles about how "people born in July fail at juggling" and how "people who wear have their ears pierced have neat handwriting"...