Independent Samples T-Test - Comparing Two Proportions

Where [math]\displaystyle{ g_1 }[/math] and [math]\displaystyle{ g_2 }[/math] are the two proportions and [math]\displaystyle{ n_1 }[/math] and [math]\displaystyle{ n_2 }[/math] are the sample sizes:

[math]\displaystyle{ z=\frac{g_1-g_2}{\sqrt{g_{12}(1-g_{12})(n^{-1}_1+n^{-1}_2)}} }[/math]

where:

[math]\displaystyle{ g_{12}=\frac{n_1 g_1 + n_2 g_2}{n_1+n_2} }[/math]

where [math]\displaystyle{ p \approx 2 \Pr(t_{n_1+n_2-2} \ge |t|) }[/math].