Dear Fang Lai, you have sent your mail to both r-devel and r-help. Please do not do this, but decide for one. Cross-posting just creates unnecessary and unpleasant junk-mail to many people.
Furthermore, neither the r-devel nor the r-help mailing lists are intended as replacements to taking a basic statistics course or reading the software manuals - rather, as supplement and last resort. The answers are provided by unpaid voluntary contributors, who appreciate that you yourself also make at least a minimal effort before going off the mailing list. Best wishes Wolfgang ------------------------------------- Wolfgang Huber European Bioinformatics Institute European Molecular Biology Laboratory Cambridge CB10 1SD England Phone: +44 1223 494642 Http: www.dkfz.de/abt0840/whuber ------------------------------------- <quote who="fang lai"> > Dear all, > I have several questions regarding fisher.test() in > R, and I'd highly appreciate any help with it. > I have a group of observations, each having people's > income, and an indicator of whether selected in or out > a program. I want to test the difference between > income of people who are in and out. > Because the distribution is far from normal, I decide > to use the fisher's exact test, using either mean or > rank as statistics. > Question 0 is: Can I do this test using fisher.test() > in R? > If so, > My first question is: Does fisher.test() offer an > option to choose the statistics? Actually it is not > clear from the help to me what statistics it uses. > Does it just compare the mean of people in and out of > the program? > My second question is: when the group is large, I > always receive a warning message such as "Fisher exact > result might not be right" when I set "hybrid=T". > When I set "hybrid=F", it does return a result of > p-value without warning message. I wonder if this > p-value is reliable or not. And, how does it get the > approximation of p-value when "hybrid=F"? Ideally, it > should randomly draw, say 1000 times, from the full > sets of permutation of assignment, and get an > approximate p-value--is this the way it works in > fisher.test( ) in R? If not, does it use another test, > or some other measure of approximation? > My last question is: when the group is small enough, > will it calculates the exact probabilities even if > hybrid=F? > Many thanks, > > Fang > > ===== > Lai, Fang > > PhD candidate > University of California, Berkeley > Department of Agricultural and Resource Economics > 314 Giannini Hall, Berkeley, CA 94720-3310 > tel: (510) 643 - 5421(O) > (510) 847 - 9811(Cell) > fax: (510) 643 - 8911 > email: [EMAIL PROTECTED] > http://www.are.berkeley.edu/jobmarket/fang.html > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
