Where g 1 {\displaystyle g_{1}} and g 2 {\displaystyle g_{2}} are the two proportions and σ g 1 {\displaystyle \sigma _{g_{1}}} and σ g 2 {\displaystyle \sigma _{g_{2}}} are their standard errors:
z = g 1 − g 2 σ g 1 2 + σ g 1 2 {\displaystyle z={\frac {g_{1}-g_{2}}{\sqrt {\sigma _{g_{1}}^{2}+\sigma _{g_{1}}^{2}}}}} ,
where p = 2 ( 1 − Φ ( | z | ) ) {\displaystyle p=2(1-\Phi (|z|))} .
