MAMBAC consistency testing

MAMBAC offers two standard internal consistency tests, the nose count test and the base rate variability test. MAMBAC allows for two analyses per pair of indicators, which means that two indicators produce two plots, three indicators produce six plots, four indicators produce 12 plots, five indicators produce 20 plots, etc. Waller s MAMBAC does not do this automatically, and the investigator has to run each analysis independently. Ruscio s software, on the other hand, is fully automatic. 

In many respects, the Waller et al. study is an exemplary taxometric report. The authors used multiple taxometric techniques and examined the construct validity of the taxon. However, three issues were not clarified in the report. First, only base rate estimates were reported and there was no discussion about shapes of the plots, so it is unclear how many of them were taxonic. Also, only one type of consistency test—cross-method consistency— was reported in the study although the different procedures were consistent with each other, it is difficult to determine the strength of each individual piece of evidence. Second, mini-scales were used for MAXSLOPE but not for the other analyses. The authors indicated that they created mini-scales because individual items are not very reliable. However, it is unclear why this would not also have been beneficial to the MAMBAC and MAXCOV analyses. Third, nuisance correlations and indicator validities were not computed. It is thus unclear how well the data conforms to CCK requirements, and how much we can trust the estimates. Moreover, this information could have been useful in assembling the DES-T. 

---