A CRITIQUE OF BULLAS PAPER ON DIVERSITY INDEXES

To be adequate, evenness indices must satisfy three criteria: (1) inde pendence of species richness; (2) independence of sample size; and (3) unambiguous relationship to evenness. I examine Bulla's evenness inde x in the light of these criteria, logically implying a failure to sati sfy the first, and experimentally proving failures to satisfy the seco nd and third. Therefore, this index is inadequate. I also examine Bull a's heterogeneity index. Being based on his evenness measure, it is al so inadequate. Moreover, the index is not the correct heterogeneity me asure under his own approach. I derive the correct index and demonstra te its kinship to the evenness index. Even this correct heterogeneity measure lacks a future because no adequate diversity indices can be ob tained from Bulla's overlap, By re-examining the savanna data with whi ch Bulla attempted to show the superiority of his index, I prove his a nalysis to be an artifact. In response to Bulla's criticism on G(2,1), I demonstrate that his argumentation is wrong, and reassure that G(2, 1) is an adequate evenness index. To conclude, I offer three general c onsiderations on index testing that, if followed, will prevent a repet ition of Bulla's errors.