Paul Kurtz takes issue with Ertel's methodology in his brief reply, "A Dissenting Note on Ertel's 'Update on the ''Mars effect,'' '" on the grounds that Ertel used European "who's who" books, which have a European bias against the eminence of American football and basketball players.
A European bias in Ertel's reference works does not entirely explain the results that appear in Table 1 of his article. Athletes cited in 2 or more of Ertel's 21 reference works are born when Mars is in one of Gauquelin's "key sectors" significantly more frequently than expected by chance, for both the KZA sample and for Gauquelin's 1982 American sample. Why should a Eurpoean bias also be a bias for athletes born with Mars in a key sector?
There is, however, a feature of the results in Table 1 that might be explained by a bias against football and basketball stars in Ertel's reference works (assuming that such a bias exists). This is Ertel's finding that only 85 of the 408 athletes in the KZA sample had two or more citations, as compared with 162 of 349 athletes in Gauquelin's 1982 sample. Since the KZA sample contained many football and basketball players while Gauquelin tended to avoid these sports, an anti-football and basketball bias in Ertel's works could result in a greater proportion of Gauquelin's sample having two or more citations in these works than the KZA sample.
In summary, I don't think that Kurtz's response resolves the central problem posed by Ertel's analysis, though it may explain the differing proportions of "high eminence" athletes between the KZA and Gauquelin samples. A resolution to the "Mars effect" mystery remains to be seen--perhaps in a new study by the French Committee for the Study of Paranormal Phenomena.