Welch's ANOVA
On Aug 22, 2011, at 11:25 PM, rafleon at highstat.cl wrote:
Hello everyone! Does someone know if there is a library that include Welch' ANOVA. I have data of catch rate (weight of lobster/pot lift, it is a continuous variable). I have two factors (two and four levels each). I cannot get variances stabilized (I applied Box&Cox transformation), so Welch' ANOVA could ids in this situation due to the fact that uses Weighted least squares. Alternatively, can I use GLM? Maybe binomial link? I'm not sure.
Not sure I see a mixed model issue being raised here, but it is typical to use Poisson models when variances are proportional to means within groups. Could have been considered count data (lobsters per pot) times a continuous variable (individual lobster wts) and then you might raise mixed model issues, but I'm guessing you didn't count the lobsters and weigh them individually. glm(wt.in.one.pot ~ fac1 + fac2 , family="quasipoisson") (When the LHS variable is not discrete, the quasi- form needs to be used or an error will be thrown.)
David Winsemius, MD West Hartford, CT