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Effects of economic crises on population health outcomes in Latin America, 1981–2010: an ecological study
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  • Published on:
    Spurious conclusions from a faulty analysis

    It is to be commended that the article on the effects of economic crises on population health outcomes in Latin America, by. Callum Williams et al., clearly explains the methods the authors used for the analysis. For that reason, the paper is a very good example of how not to use a specific type of research tool, the panel regression. In a panel regression, as in any time-series investigation of causality, a key issue is to adjust for time trends, so that variables are stationary series (1, 2). If this adjustment is missing, results are biased by trends in the variables. For example, the paper says that “after removing inflation and unemployment as controls from our regression analysis, GDP per capita increases were found to be associated with improvements in all mortality metrics.” This is just an spurious result, as in every country the trend in GDP per capita is a rising one and the trend in mortality is a declining one. If you put the number of Starbucks coffee-shops in the country rather than GDP per capita, it will be also associated with “improvements in all mortality metrics” as Starbucks are also increasing in number.
    Lack of adjustment for time trends in the variables in more than sufficient to make the results of the regression spurious, but the models in this paper have another major flaw: both unemployment and GDP per capita are included at the same time as explanatory variables in the models. Callum Williams and coauthors seem unaware that these two var...

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    Conflict of Interest:
    None declared.
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    Author Affiliation

    Please note that the author's correct affiliation is: Imperial College London.

    Conflict of Interest:

    None declared

    Conflict of Interest:
    None declared.