FIGURE 7-1 Changing relationship of fraction of suicides using a firearm (FS/S) to household gun ownership (GSS) in the US by age and sex.

This figure shows that the relationship between FS/S and household gun ownership (as reported in the GSS) varies by age and gender and appears to have changed between 1980 and 2000; for example, the difference in patterns of association between males and females has diminished substantially. Such changes suggest that the relationship between FS/S and other measures of gun ownership may be influenced by a number of social, political, and cultural factors that are not yet understood.

Third, even if the estimated correlation coefficients are valid, it is not clear how this confirms (or refutes) the utility of such a proxy as a measure of gun ownership. To the contrary, except in very specific circumstances, regressions with proxies result in biased estimators.5 Under the best cir-

5  

Maddala (1992) and Wooldridge (2000) illustrate the biases created by proxies measures in linear mean regression models.



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