is_specified_input_of statistic Wald test Wald statistic adapted from wikipedia and http://documentation.statsoft.com/STATISTICAHelp.aspx?path=glossary/GlossaryTwo/W/WaldStatistic Philippe Rocca-Serra term request from Hanna Cwiek: https://github.com/ISA-tools/stato/issues/67 the Wald statistic is a statistic is used during a Wald test, a test of significance of the regression coefficient; it is based on the asymptotic normality property of maximum likelihood estimates, and is computed as: W = b * 1/Var(b) * b In this formula, b stands for the parameter estimates, and Var(b) stands for the asymptotic variance of the parameter estimates. The Wald statistic is tested against the Chi-square distribution in the Wald test. ready for release