Friday, January 30, 2009

Danger of Self-Confidence Bias

Thanks to TechCrunch for publishing an article to amplify my post about biased decisions.

I stumbled upon the post "The Economy According to Mint", and I really do hope that Aaaron Patzer doesnt' really see the economy through the lens of data.

First of all, another thanks to Mint for publishing data, not just vague qualitative assessment of the economy but real numbers. Now, here are the reasons that the "Guest Author" should've spent the time doing something more productive.

Inclusive data sources leading to self-confidence bias

1. Let's see.... (

The traffic through just doesn't represent statistically significant set of overall population. They are well-educated, leaning towards male, ages 18+, mid-to-higher income, and no kids. The monthly visitors are around 280K in December with a majority of them being "non-regular, passers-by". (By the way, I am superposing another layer of obscurity by using Quantcast to make assumptions about the real users.)

Just to make this clear, the state of economy represented by usage is just that. The economy doesn't look as bad for the Mint users. Great for the company... maybe... but doesn't give any data outside its tiny world.

2. I personally am a Mint user, and I like it. I don't particularly love Mint, because it's go some technical glitches in connecting with a number of my other accounts. For example, I have a loan and savings account that several emails to customers service and numerous searches could not resolve. In the end, Mint has a very wrong view of my personal saving/spending/asset/liabilities trend.

I'm not trying to bash against Mint. They have a great product in process towards something significantly meaningful. I believe that they are on the right track towards something. Mint will probably face a moment sooner or later to make critical business decisions based on internally generated data like this. I smell self-confidence bias creeping into the office of Mint. The team at, please surprise me!
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