A note of correction with reference to parameters of the menstrual cycle and the efficiency of rhythm methods of contraception
James, W.H.
Population Studies 22(2): 281-282
1968
ISSN/ISBN: 0032-4728 PMID: 22091616 DOI: 10.1080/00324728.1968.10405541Document Number: 509263
Abstract Owing to a misunderstanding in regard to the data sheets, all the references to the pre- and post-ovulatory phases in Dr. Marshall's data in my paper should be interchanged. The following is a list of conclusions which may be drawn from that study: 1. Although the Farris Test is probably less efficient than had formerly been thought, there is no evidence that it is biased. 2. Within individual histories, pre-ovulatory phase variance usually exceeds post-ovulatory phase variance. 3. The variance of mean pre-ovulatory phase exceeds that of mean post-ovulatory phase among a group of women. 4. Within a group of women, there seems to be no appreciable correlation between mean pre-ovulatory and mean post-ovulatory phase. 5. It is possible that there is a true underlying positive correlation between pre- and post-ovulatory phases within a single menstrual history. 6. The standard error of the RB.T. test was estimated to exceed √6 days. 7. The variances of the phases within individual histories are probably positively correlated, so it seems that in general a variable post-ovulatory phase is not favourable to the outcome of the practice of rhythm.