Lies, damn lies, and statistics

applesandorangesThe Lancet, (Volume 372, Issue 9650, Pages 1633 – 1640, 8 November 2008) has an article entitled “The role of welfare state principles and generosity in social policy programmes for public health: an international comparative study”.  The study was funded by the Swedish Ministry of Health and Social Affairs.  An excerpt from the abstract:

Increased generosity in family policies that support dual-earner families is linked with lower infant mortality rates…

I suppose that may be true if one’s definition of “generosity” includes government redistribution of wealth.  Or maybe it isn’t true:

Infant mortality rates and old-age excess mortality rates were analysed in relation to social policy characteristics and generosity. We did pooled cross-sectional time-series analyses of 18 OECD (Organisation for Economic Co-operation and Development) countries during the period 1970-2000 for family policies…

An article from Newsweek by Dr. Bernadine Healy from 24 September 2006 gives us a warning about this sort of methodology:

First, it’s shaky ground to compare U.S. infant mortality with reports from other countries. The United States counts all births as live if they show any sign of life, regardless of prematurity or size. This includes what many other countries report as stillbirths. In Austria and Germany, fetal weight must be at least 500 grams (1 pound) to count as a live birth; in other parts of Europe, such as Switzerland, the fetus must be at least 30 centimeters (12 inches) long. In Belgium and France, births at less than 26 weeks of pregnancy are registered as lifeless. And some countries don’t reliably register babies who die within the first 24 hours of birth. Thus, the United States is sure to report higher infant mortality rates. For this very reason, the Organization for Economic Cooperation and Development, which collects the European numbers, warns of head-to-head comparisons by country. [emphasis added]

Infant mortality in developed countries is not about healthy babies dying of treatable conditions as in the past. Most of the infants we lose today are born critically ill, and 40 percent die within the first day of life. The major causes are low birth weight and prematurity, and congenital malformations. As Nicholas Eberstadt, a scholar at the American Enterprise Institute, points out, Norway, which has one of the lowest infant mortality rates, shows no better infant survival than the United States when you factor in weight at birth.

It is entirely possible that many other countries have a lower infant mortality rate than the United States.  But when trying to answer these kinds of questions, one has to be sure that the compared items or processes are commensurable.  One also has to be wary of confirmation bias.

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