similar to: A question about a linear mixed model.

Please pardon an extremely naive question. I see related earlier posts, but no responses which answer my particular question. In general, I'm very confused about how to do variance decomposition with random and mixed effects. Pointers to good tutorials or texts would be greatly appreciated. To give a specific example, page 193 of V&R, 3d Edition, illustrates using raov assuming pure

I am designing an interlaboratory validation study for a presence/absence alternative method test kit vs. a presence/absence reference method test kit. There will be 10 laboratories conducting tests using both methods. In each laboratory, there will be 5 specimens tested, each of the 5 specimens twice by both methods (alternative, standard). The total number of data are 10 x 5 x 4 = 200.

[Corrected the model formula to include "method".] I am designing an interlaboratory validation study for a presence/absence alternative method test kit vs. a presence/absence reference method test kit. There will be 10 laboratories conducting tests using both methods. In each laboratory, there will be 5 specimens tested, each of the 5 specimens twice by both methods (alternative,

Hi, I wonder if anyone can help me with specifying a right model for my analysis. I am a beginner to lme methods and though have spent already many hours studying from various books an on-line helps, I was unfortunately not able to find a solution to my problem on my own. Data structure: I studied escape behavior of three species of a prey to a predator. The prey specimens (many) were in a

Dear Friends I have a technical question about conducting 2 way repeated measures ANOVA analysis using R. 1. Data set: repeated measurement of activity over night (2 hr. intervals) repeated (within subject)factor: Hours Between subject: Species, Sex Dependent variables: specimens Here is how the data arranged for the analysis: Subject Replicate Hour Sp. Specimens 1 1 1 a 2 1 1 a

Hello All, I am looking for an R library/function that allows the specification of a custom link function in a linear mixed model. I've been using glm() in library MASS to fit fixed-effect models with a custom link but my study design demands mixed models. Any suggestions on the best R library/function to achieve this would be greatly appreciated. I have tried, to no avail, to

Dear Gideon Unless you are willing to accept uncorrelated measures in time and homogeneity of variance I would go for a linear mixed model instead. You might be surprised on how diffrent can be your results. Try; >?lme I hope that this helps Francisco >From: GIDEON WASSERBERG <wasserberg at wisc.edu> >To: "R-help at lists.R-project.org" <R-help at

Hi all, i have a dataset of 3D coordinates and can't figure out how to' tell R which One Are the individuals: I have 3 columns which i named x,y and z And then i have 2607 Lines, but each specimen is 33 Lines (79 specimens) How can i tell R to' categorize individuals every 33 Lines? Thanks in advance

The CITES Programme for monitoring the illegal killing of elephants (MIKE) is looking for a Data Scientist based at the UN Environment Programme in Nairobi, Kenya. For more details and to apply, please go to http://tinyurl.com/mikeds-p3. Deadline for applications is 3 July. Org. Setting and Reporting The United Nations Environment Programme (UNEP) is the United Nations system's designated

Dear all, I'm building binomial mixed-model using lme4 package. I'm able to obtain outputs properly except when I include two particular variables: date (from 23 to 34; 1 being to first sampling day) and Latitude (UTM/100 000, from 55.42 to 56.53). No "NA" is any of those variables. In those cases, I get the warning message: "nlminb failed to converge" I tried to

Dear all, I have some questions regarding the validity an implementation of statistical tests based on linear models and loess. I've searched the R-help arhives and found several informative threads that related to my questions, but there are still a few issues I'm not clear about. I'd be grateful for guidance. Background and data set: I wish to compare the growth and metabolism

I'm trying to create maps of reptile abundance in different states & counties using data from Herp.net, which provides lists of specimens with the places that they were found. First I would like to parse the list by state using 2-letter abbreviations, since I'm focusing on certain regions. To do this, I've been trying to create a vector (state2) that gives all state names as

*Thanks* all those who took the time to help me (even if the "question" was not related to - the use of - R). Now I think I can soundly make my point w/ the referee (can I use your replies? If so I intend to properly cite its use?!?). Regards, Eduardo Esteves ps - Sorry for not explaining the "biological details" of my posting: RNA/DNA is the ratio of RNA content to

R-help: I am trying to decide between using a multiple linear regression or a linear mixed effects model for my data: model1 <- lm (responsevariable ~ predictor1 + predictor2 + predictor3 + predictor4, data= data) model2 <- lme (responsevariable ~ predictor1 + predictor2 + predictor3 + predictor4, random = ~1 | site, data= data) anova (model1, model2) but I keep getting the

I measured nitrate concentration and primary production (PP) biweekly for 23 months in one headwater stream. I would like to use linear regression to determine if PP is related to nitrate concentration. My dataframe is called "data" and consists of the vectors Rdate, PP, and nitrate. Rdate is the observation date in class "date" and PP is primary production. I first

I am trying to apply a permuation-based MANOVA (Anderson 2001) to a set of morphological data from three ecomorphs of fish reared under two different conditions and measured at two points during ontogeny. I will supply a distance matrix based on Procrustes distances calculated outside of vegan. I have not found an example of a design such as this for adonis. However, I have designed my factors

I Dears, if that wouldn't take u too much effort I'd like to ask for a swift opinion: I have a alinear (mixed effect) model that I wish to run as a piecewise one. When I predict the values Iget quite some odds and disturbing results: The predicted stright line after the break point is not straight at all, instead behaves like if it was a hig order polynomial or something similar!!!! I

I would like to draw a sample from a linear mixed model y=Xb+Zu+e which has been fitted with lme(), i.e. a model y ~ N(Xb, C), where C=Z cov(u) Z' + cov(e). I've tried to figure out how to extract C from an lme object, because that would solve my problem when also using the predict() function, but without any luck. Can anyone help on that?

Hello, I wish to learn how to extract best linear unbiased predictor values from a linear mixed model of repeated measures on individuals which has a random error structure (random =~ 1|individual). Thanks for your time, Kind regards Matt -- Matt Robinson Institute of Evolutionary Biology University of Edinburgh

Hi all, I have searched for a long time to find out R program about V ariable S election for GLMM (Generalized Linear Mixed Model). I saw several great R packages for V ariable S election. I  also found several R packages for GLMM. But, I did not find yet R package about V ariable S election for GLMM even though sevel  papers about it have been published.   In fact,  I need V ariable