Pareto distributions in online casino gambling: Sensitivity to timeframe and associations with self exclusion

•Online gambling engagement is highly skewed and exceeds the conventional Pareto (80:20) rule.•The most engaged online gamblers display elevated rates of self-exclusion as a marker of likely gambling harm.•Pareto estimates from one month data is lower than the Pareto estimates from one year data.•Pareto estimates from short time windows may under-estimate the degree of distributional skew.