  Summary
  Background Claims made in science papers are coming under increased scrutiny
with many claims failing to replicate. Meta-analysis studies that use
unreliable observational studies should be in question. We examine the
reliability of the base studies used in an air quality/heart attack
meta-analysis and the resulting meta-analysis.
  Methods A meta-analysis study that includes 14 observational air
quality/heart attack studies is examined for its statistical reliability. We
use simple counting to evaluate the reliability of the base papers and a
p-value plot of the p-values from the base studies to examine study
heterogeneity.
  Findings We find that the based papers have massive multiple testing and
multiple modeling with no statistical adjustments. Statistics coming from the
base papers are not guaranteed to be unbiased, a requirement for a valid
meta-analysis. There is study heterogeneity for the base papers with strong
evidence for so called p-hacking.
  Interpretation We make two observations: there are many claims at issue in
each of the 14 base studies so uncorrected multiple testing is a serious issue.
We find the base papers and the resulting meta-analysis are unreliable.

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