Sunday, November 4, 2007

Data, statistics, facts - what are they?

I am confused because of this article by Prof. Mankiw - Beyond Those Health Care Numbers. Mark Thoma points out the following:

He should also know that life expectancy from birth, which he is using in his arguments about different death rates for infants and the young, is not the only or even the best way to make life expectancy comparisons (as opposed, to say, the life expectancy at age 30, age 40, etc., i.e. given that you've already made it through the infant and young adult years).

The data is not disputed, nor are the statistics (e.g. the average life expectancy), but the facts (i.e. the interpretation of the data/statistics) are disputed. What is the correct number to present? Unfortunately, this reminded me of a line I wrote for a review of Econospinning by Gene Epstein:

...this book is an indictment of economics and statistics and a reminder as to why the average person hates both.

The full review of Econospinning is below. (I didn't try to shop this around. It's a little pathetic.)

In this book, Gene Epstein, the Economics editor at Barron’s presents examples of how employment numbers such as the unemployment rate, labor force participation rates and wages can be interpreted or in this case, misinterpreted or manipulated. Indeed almost two thirds of this book is devoted solely to various employment numbers and how they can be misused. In an interesting aside he recounts how President Richard Nixon thought that Jews holding high positions in the Bureau of Labor Statistics were undermining him and proceeded to have them fired.

Almost half the book is spent criticizing numbers presented by Paul Krugman in his New York Times column. Along the way, Epstein also tries to straighten the record on former Federal Reserve Board Chairman Alan Greenspan. Greg Ip, the Wall Street Journal reporter had given a positive review of the chairman’s tenure and Epstein exposes what he calls the Greenspan myths. He also takes aim at the CNBC morning show Squawk Box, newscaster Lou Dobbs at CNN, author Barbara Ehrenreich’s bestselling book “Nickel and Dimed” and two chapters of the bestselling book “Freakanomics” by University of Chicago economist Steven Levitt and his co-author Stephen Dubner.

Given that Epstein’s theme is how to properly interpret numbers released by various government agencies, the book is scattered with various boxes on how ratios should be calculated. Sadly, this book is an indictment of economics and statistics and a reminder as to why the average person hates both.

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