search for: invertebrates

...distance="bray", k=3, trymax=100, wascores=TRUE, trace=TRUE, zero="add") invert.mds<-metaMDS(bugcal.a, distance="bray", k=3, trymax=100, wascores=TRUE, trace=TRUE, zero="add"), where fish.data and invert.data are site-by-abundance matrices for fish and invertebrates, respectively. I have then used protest() to test the significance between the two ordinations: protest.results<-protest(fish.mds, invert.mds, scale=TRUE, symmetric=TRUE, permutations=999) The problem is, the results of the protest analysis seem to be affected by the original ordering of site...

Hi! I wish to know if there is any R forum which is meant only for Statistics? I mean where we can clarify our statistics doubts and seek knowledge. I know there are lot many books and internet sites, but 'R forum' has altogether different standard and very high level and one can learn a lot from them. Regards Vincy [[alternative HTML version deleted]]

Hi everybody, I used randomForest to regress invertebrates abundances in least impaired river reaches from some environmental parameters. Then I used these models to predict invertebrates abundances in impaired reaches. Now I would like to model the deviation (observation - prediction) with a set of chemical parameters to see if the deviations from predic...

Greetings How do I do this in R? Checking the Cran site produces a bewildering array of packages that I can't seem to find to load. Surely the main program has this function? Cheers Kurt *************************************************************** Kurt Lewis Helf, Ph.D. Invertebrate Ecologist National Park Service Cumberland Piedmont Network P.O. Box 8 Mammoth Cave, KY 42259 Ph:

Hello all I'm trying to do a simulation that involves identifying the minimum point between two peaks of a (usually) bimodal distribution. I can do this easily if there are only two peaks: CnBdens<-density(Ys/Xs) #probability density function for ratio of Ys to Xs for(p in 1:512) ifelse(CnBdens$y[p]>CnBdens$y[p-1],peak1<-p,break) #identifies first peak in probability

I am trying to make some plots for a poster. Each one needs to be 6 inches by inches. Right now the fonts are too small and the plots don't read well on my poster. I am pretty much an R newbie and I can't figure out how to change the fonts. It would also be nice to know how to specify the size of the plot and maybe how to save the plots as jpeg files. Any help would be much appreciated! I

Dear all, I am facing some problem with how to fit a "Baseline category Logit model" with R. Basically I am considering famous "Alligator" data as discussed by Agresti. This data can also be found here: https://onlinecourses.science.psu.edu/stat504/node/174 (there is also an accompanying R file, however the underlying R code could not load the data properly!!!) Below are

Dear R, I am using stepwise multiple glm to select a subset of variables using the step command. My question is how do you calculate the percentage variance for each parameter in the reduced model. An example of my code thus far is, fit<-glm(Abalone~offset(Area)+Sessile invertebrates+Bare rock+ NCA + Encrusting red algae, family = poisson ()) step(fit) fit1<-glm(Abalone~offset(Area)+Bare rock+NCA+Encrusting red algae, family=poisson()) Thanks in advance Beth Strain _________________________________________________________________ What are you waiting for? Join Lavalife...

Hello! I am working on a manuscript on sexual dimorphism in an aquatic invertebrate, where we have estimated sexual dimorphism (SD) for 7 different traits in four populations (a total of 28 SD-estimates). We have used the following formula for estimating SD: 100 * (mean male trait value - mean female trait value)/overall trait mean). Then, we have used these SD-estimates to perform a GLM against

Greetings I am attempting to plot observations of a cave aquatic invertebrate dating from 1901-2004. I can come up with a nice lattice plot of the eight sites from which I have data easily enough. However, I'd like to be able to highlight the 0 observations on the plots, i.e., attempts to find it at the site were unsuccessful. I'd like to be able to highlight these observations

Dear list, I performed a multivariate analysis on freshwater invertebrates data. So I obtained coordinates of my samples on the axes defining the first factorial plane (F1 and F2). I would like to see if the positions on my factorial plan could be linked to levels of impairment ('low' vs 'significant') for several water quality pressure categories and whi...

I'm interested in analysing some of my data using multinomial regression. I have been using nnet's multinom so far. However, I found that some of the data shows overdispersion and hence want to change to robust multinomial regression, package: multinomRob I have succesfully implemented Agresti's (2002) alligator example (chapter 7, p 268) using the option MLEonly=TRUE as there are too