Asian J Androl 2005; 7 (1): 108

This web only provides the extract of this article. If you want to read the figures and table, please reference the PDF full text on Blackwell Synergy. Thank you.

^.Letters to the Editor^.

Reply to `Statistical testing and distribution for lead chloride toxicity'

Maria de Lourdes Pereira¹, J. Ramalho-Santos²

¹Department of Biology, University of Aveiro, 3810 Aveiro, Portugal
²Department of Zoology, University of Coimbra, Coimbra, Portugal
Tel: +351-234-370-770, Fax: +351-234-426-408; E-mail: lpereira@bio.ua.pt

Received 2004-11-12 Accepted 2004-11-12

Dear Sir,

We are very grateful for the letter written by Dr Lange, and indeed apologize for the mistakes noted in the wording of our text regarding statistical analysis. This was due to changes carried out while revising the manuscript at the request of reviewers, whom we thank for, pointing out several issues that were actually similar to those noted by Dr. Lange. Unfortunately, we were unable to describe and discuss our findings properly in the context of the revision.

To clarify: in Table 2 we compared controls and treatments (columns 1 and 2, or 3 and 4) using the t-test (i.e. two groups at a time, as noted by Dr. Lange). We also compared controls for lead injection and recovery for the same variable (columns 1 and 3). The P values presented in the table as significant are from those compari-sons. At the request of reviewers, we indeed performed further analysis on our data using one-way ANOVA, to compare all columns, with post-tests taking into account all comparisons (Bonferroni and Tukey). These tests showed that the only significant differences were the ones already discussed in the first version of the Manu-script. However, this was swiftly and inappropriately worded in the final version of the manuscript, and, we now realize, was not clear at all to readers.

We have since also performed the Kruskal-Wallis test (for reasons Dr. Lange clearly explains in his letter) with Dunn's post-test, to similar results.

A few short clarifications: The mice were bought on several different occasions from a supplier, in numbers that imply several litters, and assigned randomly to different experimental groups. Although we cannot be sure, we believe there should be no relatedness issue in this case. In regard of semen analysis, following the WHO guidelines for human semen [1], we evaluated motility, sperm abnormalities and acrosome reaction in terms of percentage.

This is also not at all uncommon when evaluating sperm from animal models, given that different procedures (treatments, genetic manipulations, etc.) may have an effect on sperm count, thus rendering total number comparisons misleading.

References

• 1 World Health Organization. WHO Laboratory Manual for the Examination of Human Semen and Sperm-Cervical Mucus Interaction (Fourth Edition). Cambridge: Cambridge University Press; 1999.