Box and whisker plot showing the absolute bias (μmol/L) for the enzymatic technique. The box represents the 25th, 50th and 75th percentile; the whiskers represent the 5th and 95th percentile. The extremes, defined as values more than three times the interquartile range, are the signs above and underneath the whiskers. The grey line represents the 0 μmol/L bias line.
Drion et al. BMC Nephrology 2012 13:133 doi:10.1186/1471-2369-13-133