From owner-drosophila@net.bio.net Sun May 05 23:00:00 1996 Path: biosci!ihnp4.ucsd.edu!swrinde!newsfeed.internetmci.com!in1.uu.net!news.ultranet.com!bigboote.WPI.EDU!news3.near.net!news.ner.bbnplanet.net!news.cshl.org!elvira.cshl.org!user From: jonesc@cshl.org (Chris Jones) Newsgroups: bionet.drosophila Subject: Re: Fly Crossing Date: Mon, 06 May 1996 13:38:35 -0500 Organization: Cold Spring Harbor Laboratory Lines: 20 Message-ID: References: <318A7422.37B1@odyssee.net> NNTP-Posting-Host: elvira.cshl.org X-Newsreader: Yet Another NewsWatcher 2.1.3 In article <318A7422.37B1@odyssee.net>, John Chan wrote: > I'm I student from Montreal and our biology class is experiencing fly > crossing. My team crossed Wild males and dumpy sepia females(PxP). Then > we crossed the offsprings and we obtained these results: 268 Wild Wild, > 64 Wild Sepia, 76 Dumpy Wild and 17 Dumpy Sepia. The Chi-Square Test > rejected our results (Our hypothesis for the ratio is 9:3:3:1). > Considering the fact that there was no experiment or identifying errors, > how can I explain the rejection of the results by the Chi-Square Test. John -- If you assume a 9:3:3:1 ratio is correct, what sorts of numbers would you expect? If you anchor your estimate to the wild-type count of 268, then you'd expect about 90 sepia, 90 dumpy, and 30 sepia,dumpy flies. You only observed 70-85% of the sepia and dumpy flies you expected, and only about 50% of the double mutants expected. Does this suggest anything? -- Chris Jones (jonesc@cshl.org) .