Posts Tagged ‘ science ’

Football and statistics, on HBR!

January 30, 2015
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I was asked to adapt my earlier post for the HBR audience, and the new version is now up on HBR. Here is the link. I'm happy that they picked up this post because most business problems concern reverse causation. A small subset of problems can be solved using A/B testing, but only those in which causes are known in advance and subject to manipulation. Even then, Facebook got into…

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Limits of statistics, and by extension data science, as illustrated by Deflate-gate

January 27, 2015
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Limits of statistics, and by extension data science, as illustrated by Deflate-gate

A number of readers sent me Warren Sharp's piece about the ongoing New England Patriots' deflate-gate scandal (link to Slate's version of this) so I suppose I should say something about it. For those readers who are not into American football, the Superbowl is soon upon us. New England, one of the two finalists, has been accused of using footballs that are below the weight requirements on the rulebook, hence…

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How Optimizely will kill your winning percentage, and why that is a great thing for you (Part 1)

January 23, 2015
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In my HBR article about A/B testing (link), I described one of the key managerial problems related to A/B testing--the surplus of “positive” results that don’t quite seem to add up. In particular, I mentioned this issue: When managers are reading hour-by-hour results, they will sometimes find large gaps between Groups A and B, and demand prompt reaction. Almost all such fluctuations result from temporary imbalance between the two groups,…

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Three reasons to doubt the GDP-gas price conjecture

January 20, 2015
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Dragged by infectious incuriosity, the financial press ran with the story that falling gasoline prices (50% drop in 6 months) is "the best economic stimulus one can get". See former Deputy Treasury Secretary Robert Altman on CNBC, Business Insider's "cheap gas boost", Wall Street Journal citing the "low oil prices as an effective tax cut for consumers", New York Times quoting a Citigroup analyst claiming a global > $1 trillion…

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Trifacta revisited: tackling a Big Data problem

January 12, 2015
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During my vacation, I had a chance to visit Trifacta, the data-wrangling startup I blogged about last year (link). Wei Zheng, Tye Rattenbury, and Will Davis hosted me, and showed some of the new stuff they are working on. Trifacta is tackling a major Big Data problem, and I remain excited about the direction they are heading. From the beginning, I am attracted by Trifacta’s user interface. The user in…

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A great start to the year

January 1, 2015
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A great start to the year

I'd like to start 2015 on a happy note. I enjoyed reading the piece by Steven Rattner in the New York Times called "The Year in Charts". (link) I particularly like the crisp headers, and unfussy language, placing the charts...

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Proxy unmasking

December 25, 2014
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Consider this paragraph from a FiveThirtyEight article about the small-schools movement (my italics): Hanushek calculated the economic value of good and bad teachers, combining the “quality” of a teacher — based on student achievement on tests — with the lifetime earnings of an average American entering the workforce. He found that a very high-performing teacher with a class of 20 students could raise her pupils’ average lifetime earnings by as…

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Cloudy and red

December 23, 2014
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Cloudy and red

Note: I'm traveling during the holidays so updates will be infrequent. Reader Daniel L. pointed me to a blog post discussing the following weather map: The author claimed that many readers misinterpreted the red color as meaning high temperatures when...

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Another example of misleading time-based correlation

December 15, 2014
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Another example of misleading time-based correlation

On my sister blog last week, I wrote about how to screw up a column chart. The chart designer apparently wanted to explore whether Rotten Tomato Scores are correlated with box office success, and whether the running time of a movie is correlated with box office success. In either case, the set of movies is a small one, those directed by Chris Nolan. Here is a better view of the…

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How to face the mid-life crisis in A/B Testing

December 10, 2014
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There have been few updates as I was working on things for other people. One of these things showed up today. Here is an excerpt from the beginning of my new article on HBR: For over 10 years and at three companies, I set up and ran A/B testing programs, in which we test a new offer with half a sample against a control group which doesn’t get a new…

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