search for: rapsomaniki

...t. Are you aware of any reputable places (academic or not) that use R? (e.g. maybe you work for them) I would be really grateful for any advice on this. Also suggestions on arguments I could use to persuade them that R is so much better than Excel would be very much appreciated. Many Thanks Eleni Rapsomaniki

You need to give us more details, like how you call randomForest, versions of the package and R itself, etc. Also, see if this helps you: http://finzi.psych.upenn.edu/R/Rhelp02a/archive/32918.html Andy From: Eleni Rapsomaniki > > Dear all, > > I am trying to train a randomForest using all my control data > (12,000 cases, ~ 20 explanatory variables, 2 classes). > Because of memory constraints, I have split my data into 7 > subsets and trained a randomForest for each, hoping that > using comb...

...ther similarly super-efficient function)? example: #Suppose a matrix: m1=cbind(1:5,1:5,1:5) #The aim is to create a new matrix with every column containing the cumulative sum of all previous columns. m2=m1 for(i in 2:ncol(m1)){ m2[,i]=apply(m1[,1:i],1,sum) } m2 Many thanks in advance Eleni Rapsomaniki Research Associate Strangeways Research Laboratory Department of Public Health and Primary Care University of Cambridge ?

...0,4.2,1.1) plot(density(r2), col="blue") lines(density(r1), col="red") Is there a way in R to compute/estimate the point(s) x where the density of the two distributions cross (ie where x has equal probability of belonging to either of the two distributions)? Many Thanks Eleni Rapsomaniki PhD student Birkbeck College, UK

...ks, adjusted for the individual's covariates? The only thing that seems to come close is the cuminc function from cmprsk package, but I would like to adjust for more than one covariate (it allows you to stratify by a single grouping vector). Any help/tips will be extremely appreciated. Eleni Rapsomaniki Research Associate Cambridge [[alternative HTML version deleted]]

...can plot it the polynomials and fitted coefficients as: plot(0.407*I((age/100)^-2) + -4.96*I((age/100)^-0.5) ~ age, GBSG) But I can't work out how to get a 95% confidence interval for this curve... Any suggestions? I could bootstrap it, but is there a mathematical solution? Many thanks Eleni Rapsomaniki Medical Statistician UCL, London

...I have two symmetrical distance matrices and want to compute the correlation coefficient between them (after turning them into vectors). Is there a way of selecting only the upper triangular part of each matrix, then convert this into a vector so I can compute the correlation? Many Thanks Eleni Rapsomaniki

Hi I found on google that there is an implementation of hot-deck imputation in SAS: http://ideas.repec.org/c/boc/bocode/s366901.html Is there anything similar in R? Many Thanks Eleni Rapsomaniki

...). The following: updated.forml=update(forml, ~ . -A) #gives me this: #Surv(time, status) ~ x1 + x2 + x3 + x4 + B + x5 + strata(sex) + A:x3 + A:x4 + B:x5 #but I want this: #updated.forml=as.formula("Surv(time, status) ~ x1+x2+x3+x4+B*x5+strata(sex)") Any ideas? Thanks in advance Eleni Rapsomaniki Research Associate Strangeways Research Laboratory Department of Public Health and Primary Care University of Cambridge ?

...mory constraints, I have split my data into 7 subsets and trained a randomForest for each, hoping that using combine() afterwards would solve the memory issue. Unfortunately, combine() still runs out of memory. Is there anything else I can do? (I am not using the formula version) Many Thanks Eleni Rapsomaniki

...but couldn't find much theory about the "mean" imputation method. Are there any good papers to explain the background behind each imputation option in MICE? I would really appreciate any comments on the above, as my understanding of statistics is very limited. Many thanks Eleni Rapsomaniki Birkbeck College, UK

...n data, handles categorical data better etc)? Also, is there a way of evaluating the predictive ability of each parameter in the bayesian model as it can be done for random Forests (through the importance table)? I would appreciate any of your comments and suggestions on these. Many thanks Eleni Rapsomaniki

Dear R users, I know one way to see the code for a hidden function, say function_x, is using default.function_x (e.g. summary.default). But how can I see the code for imported packages that have no namespace (in this case Design)? Many Thanks Eleni

...survplot(survfit(Surv(time,status) ~ quantile(age,3), data=veteran) #will not work ideally I would like to superimpose estimates from cph models, which automatically fit the 2nd to 4rth quantiles for age, so I need the age groups to be grouped the same. Any help greatly appreciated! Eleni Rapsomaniki

...at predictor means. Use cph(...,x=T,y=T) (and don't use linear.predictors=) for better estimates. I would like to turn this specific warning off, as it makes it difficult to detect other (potentially more crucial) warnings generated by other parts of my code. Is there a way to do this? Eleni Rapsomaniki Research Associate Strangeways Research Laboratory Department of Public Health and Primary Care University of Cambridge ?

Hi, I am using the function "nomogram" in the rms package for survival analysis. How is the order in which variables determined and how can I change it? I use it with a cph() model. Many Thanks Eleni Rapsomaniki Clinical Epidemiology Group Department of Epidemiology and Public Health University College London

...eta1, comb.fixed=F, comb.random=F, rightcols="effect",leftcols="studlab") forest(meta2, comb.fixed=F, comb.random=TRUE, leftcols="studlab",leftlabs="") #they are superimposed... which is not what I want. Any hints/ideas much appreciated! Many thanks Eleni Rapsomaniki Research Associate Department of Public Health and Primary Care University of Cambridge

...vs observed probabilities). Any other functions I should be aware of? Also, has anybody come across an implementation of the statistic described in: "A global goodness of fit statistic for Cox regression models" by Parzen & Lpisitz, Biometrics 55, 1999 Many thanks in advance Eleni Rapsomaniki Research Associate Strangeways Research Laboratory Department of Public Health and Primary Care University of Cambridge ?

...0.7333333 0.7333333 0.7333333 #even worse, if I sort tau in ascending times I get 0's UnoC(Surv.rsp, Surv.rsp.new, lpnew, time=sort(tau)) [1] 0 0 0 0 0 0 0 0 0 0 This is a potentially very useful function so it would be great if someone could explain the behaviour here. Many thanks Eleni Rapsomaniki Research Associate/Statistician Strangeways Research Laboratory Department of Public Health and Primary Care University of Cambridge ?

...lt;=t, cause=k1|x)=Sum(u=0, ..., u=t) {hazard_k(u;x)*S(u;x)} where S(u;x) = exp{-sum_of_k(sum(hazard_k(u))} I have searched extensively for an implementation of this in many packages, but it appears that more complex approaches are more commonly implemented, such as timereg package. Eleni Rapsomaniki Research Associate Strangeways Research Laboratory Department of Public Health and Primary Care University of Cambridge [[alternative HTML version deleted]]