Where \(\hat{\beta}_1\) and \(\hat{\beta}_2\) are two coefficients and \(n_1\), \(n_2\) are their effective sample sizes and \(se_1\) and \(se_2\) are their standard errors, the test statistic is:

\[\begin{align} t=\frac{\hat{\beta}_1-\hat{\beta}_2}{\sqrt{se^2_1 + se^2_2}} \end{align},\]

where:

\(p = 2\Pr(t_v \ge |t|),\)

\(v = \frac{(se^2_1+se^2_2)^2}{se^4_1/(n_1-b)+se^4_2/(n_2-b) },\)

\(b\) = Bessel's correction.