Classification matrices for selected regression models illustrating the prediction accuracy of variables examined either individually or in combination.

a<p>The percentage of pregnancies correctly classified as a proportion of those blastocysts predicted to result in a successful pregnancy.</p>b<p>The percentage of embryos correctly classified as resulting in no pregnancy and pregnancy (the hit ratio).</p>c<p>Conventional variables based on the stage and morphological quality code of blastocysts at the time of transfer.</p>d,e<p>Different letters indicate a significant difference (P<0.05). Data were analyzed with the Yates' corrected χ² test.</p>