Table 4 Comparison of the log-binomial method and the robust Poisson method for vaso-constriction associated with the logarithm of rate and logarithm of volume of inspired air*
Independent variableLog PR estimate† (SE)p Value
Log-binomialRobust PoissonLog-binomialRobust Poisson
Log(rate)1.3132 (0.3362)1.5578 (0.4270)<0.001<0.001
Log(volume)0.7715 (0.1960)1.4614 (0.3510)<0.0010.0000
  • *Wald tests were used for the robust Poisson method, and likelihood ratio tests were used for the log-binomial method. The latter were obtained by fitting a model without the effect being tested, and calculating minus twice the difference in log likelihoods to get a χ2 test statistic and p value. In case the log-binomial did not converge, the COPY method approximation was used.

  • †The intercept estimate was −1.5147 for the log-binomial method and −1.8311 for the robust Poisson method. Of the 39 probability estimates, three were greater than unity for the robust Poisson method, and the largest was 1.82.