Statistical analyses were appropriate. Although the study authors did not specify if they tested or confirmed homogeneity of variance prior to conducting the tests, it is assumed because it was noted that parametric and nonparametric tests were conducted and that regression ANOVA was tested on log-transformed data.

It should be noted that in table 1 of demographic characteristics there were a total of 180 children in the high fluoride group, 91 in the high-As group, and 253 in the medium-As group, but in the IQ results the n was 180 in the high-As group, 91 in the medium-As group, and 253 in the high-fluoride group. It is assumed that the data in Table 1 was mislabeled and that the numbers in the results table are correct. This is based mainly on the fact that the number of subjects in the other results reflects the numbers provided in the IQ results and not the Demographic charcateristic table.

Wang 2007

Risk of bias

Epidemiological study populations

HAWC