Thread by @nicolas_sommet

The Spirit Level has been cited ≈10K times (≈700 times in 2018).

The book is straightforward: It uses cross-sectional data to show negative effects of #IncomeInequality on health.

The problem: It does NOT hold up to scrutiny.

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#1 🍒-picking.

In the Spirit Level, some countries are excluded from the analysis without justification. When including these countries and using the latest estimates available, the core findings of the book disappear. [2/5]

#2 A second bite at the 🍒

Papers using large survey data with much more countries fail to reproduce the findings. E.g., Jen et al. shows that income inequality actually reduces the chances to report a poor health (especially, in developing countries). [3/5]

#3 The 🍒 on the cake

Meta-analyses suggest that the effects of inequality on physical and mental health are trivial and/or unreliable. The pooled effect sizes are very small and there are extreme levels of inconsistency across studies.

So why is the Spirit Level still widely and uncritically cited (see below)? I’m not sure… A political bias, maybe. Anyway, it makes me feel that science is def not self-correcting here.

More to come soon.

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