Inhibin is a hormone thought to be involved in the regulation of sex hormones during the estrus cycle. It has been recently isolated and characterized. Most assays have been bioassays based on...

Inhibin is a hormone thought to be involved in the regulation of sex hormones during the estrus cycle. It has been recently isolated and characterized. Most assays have been bioassays based on cultured cells, which are complicated. Less cumbersome radioimmunological assays (RIAs) have been developed, but they are less sensitive than bioassays. Robertson and coworkers* developed a new RIA for inhibin and, as part of its validation, compared it to standard bioassay. They made this comparison in two different phases of the ovulation cycle, the early follicular phase and the midluteal phase (the data are in Table D-10, Appendix D). If the two assays are measuring the same thing, there should be no difference in the relationship between RIA R and bioassay B in the two different phases. A. Is there a difference? B. If the two assays are measuring the same thing, the slope should be 1.0. Is it?

Table D-10