Data on tracing handguns are unreliable

[Gunco]

Traces are sometimes useful for law enforcement. However, because of selection bias in finding and determining which guns to trace   sometimes intentional and sometimes not but always impossible to correct or adjust for   no study based on tracing data is worth the paper it's printed on, regardless of how sophisticated or honest the analysis following the data collection. As the acronym has it, GIGO ("garbage in, garbage out").

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