z = p ^ 1 − p ^ 2 p ^ q ^ ( 1 n 1 + 1 n 2 ) {\displaystyle z={\frac {{\hat {p}}_{1}-{\hat {p}}_{2}}{\sqrt {{\hat {p}}{\hat {q}}({\frac {1}{n_{1}}}+{\frac {1}{n_{2}}})}}}}
z = .65 − .43 .54 × .46 ( 1 4006 + 1 3315 ) {\displaystyle z={\frac {.65-.43}{\sqrt {.54\times .46({\frac {1}{4006}}+{\frac {1}{3315}})}}}}