Posts Tagged ‘ Current Affairs ’

Composite ranking and numbersense

February 25, 2015
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Composite ranking and numbersense

Chapter 1 of Numbersense (link)uses the example of U.S. News ranking of law schools to explore the national pastime of ranking almost anything. Since there is no objective standard for the "correct" ranking, it is pointless to complain about "arbitrary" weighting and so on. Every replacement has its own assumptions. A more productive path forward is to understand how the composite ranking is created, and shine a light on the…

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A startling chart about income inequality, with interpretative difficulties

February 24, 2015
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A startling chart about income inequality, with interpretative difficulties

Reader Robbi B. submitted the following chart posted to Twitter by Branko Milanovic: The chart took a little time to figure out. This isn't a bad chart. Robbi wondered if there are alternative ways to plot this information. The U.S....

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Anyone still remember Groupon?

February 18, 2015
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Anyone still remember Groupon?

I just did a guest lecture at a New School journalism class. While preparing for the class, I pulled the sad stock chart for GRPN (Groupon): If you bought the hype in 2011, you'd have lost 70% of your investment ($25 to $7). Given what we know today, it's hard for people to feel the hype that the media helped fuel in those days. As a reminder, here is the…

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Fixing the visual versus fixing the story

February 13, 2015
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Fixing the visual versus fixing the story

It's great for me when my friend Alberto Cairo lent a helping hand (link). Here is the original chart showing deaths in African and Middle East countries due to recent unrest: This is Cairo's redesign: There is no doubt the...

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Deflate-gate, Part 2: not average != extreme, and Sunday talk shows

February 2, 2015
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Last week, I pointed out the futility of using data as proof or disproof in Deflate-gate. Emphatically, a case of "N=All" does not make things better. I later edited the post for HBR (link). In this post, I want to address a couple of more subtle technical issues related to the Sharp analysis, which can be summarized as follows: 1. New England is an outlier in the plays per fumbles…

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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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Three short lessons on comparisons

January 29, 2015
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Three short lessons on comparisons

I like this New York Times graphic illustrating the (over-the-top) reaction by the New York police to the Eric Garner-inspired civic protests during the holidays. This is a case where the data told a story that mere eyes and ears...

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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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