similar to: Preconditions for a variance analysis

Hi all, I just want to understand how R computes p-value in a simple linear regression model? The reason is that in Matlab in the function which "evaluate standard errors for multivariate normal regression", it just provide estimates and standard errors, without giving out p-value, It computes t-statistics as follows: abs(beta_hat/std_beta_hat) how to go further to get p-value?

Has anyone implemented a t-test with the effective sample size correction proposed by Dale and Fortin, Ecoscience 9(2):162-167, 2002, using a discussion by Cressie, 1993, page 15? thanks, Denis

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Hello everyone! I'm trying to plot some mathematical expression along my axis, but demo(plotmath) did not have the symbol I was looking for. In particular, I would like to denote the mean of an observable by writing <k> which I tried to enter with expression(group("<", k, ">")) However, my naive try doesn't work and the help doesn't want to tell me,

Hello, I'm currently using a boxplot to visualize data for three different models. As I have three models, I'm plotting three parallel boxplots for each factor. This works fine - what I need now is a line connecting the medians of each boxplot of each model. I want to do this in order to visualize the trend that one of the models exhibit. Basically, I want to plot a curve for each model

Hi everyone, Suppose I have a count the occurrences of positive results, and the total number of occurrences: pos <- 14 total <- 15 testing that the proportion of positive occurrences is greater than 0.5 gives a p-value and confidence interval: prop.test( pos, total, p=0.5, alternative='greater') 1-sample proportions test with continuity correction data: 14 out of

Hello all, I have read as many merge issues as I possibly could tonight and although I presume this is a small error, I have not found the solution to my problem. I'm trying to merge two data sets: dat0 and TransTable. As you can see below, dat0 has 8000 rows, whereas TransTable has 47296 rows. I would expect when I merge the two data sets, with all.x=F, and all.y=F, that the

Dear all, I am running R 2.4.1. > library(siggenes); > library(multtest); > cl<-rep(c(0,1),c(3,3)); > sub<-exprs(AffyExpData[,c(1:3,7:9)]); > gn<-geneNames(AffyRAwData); > sam.out<-sam(sub,cl,rand=123,gene.names=gn); We're doing 20 complete permutations > sam.out SAM Analysis for the Two-Class Unpaired Case Assuming Unequal Variances Delta p0

Dear R user, I am trying to reproduce the results in Montgomery D.C (2001, chap 13, example 13-1). Briefly, there are three suppliers, four batches nested within suppliers and three determinations of purity (response variable) on each batch. It is a two stage nested design, where suppliers are fixed and batches are random. y_ijk=mu+tau_i+beta_j(nested in tau_i)+epsilon_ijk Here are the

Dear all R users : I am a IT student with few statistical background and new R user for only have two month exprience. I have a data named medcost, import by read.table() as follow for example (real dataset has 500 cases), the heander id means case id, member means members in a family and cost is the family pay for medical cost every 6 months. id member cost 1 4

Hi, I am trying to run a multilevel model with time nested in people and people nested in dyads (3 levels of nesting) by initially running a series of models to test whether the slope/intercept should be fixed or random. The problem that I am experiencing appears to arise between the random intercept, fixed slope equation AND. (syntax: rint<-lme(BDIAFTER~BDI+WEEK+CORUMTO,

Hi I just started using RGui.exe under widnows. I have a text file containing date arranged in columns and rows, each column has the same format, each row with different formats. 3 of the columns are something like this 1/12/2006 3:59:45 PM I need to calculate the different in seconds between 2 selected periods using their row’s index My solution: Read the file in a data frame and

Hello :) I have two data frames, one has properties taken on a piece by piece basis and the other has performance on a lot by lot basis. I wish to combine these two data frames but the problem is that each lot has multiple pieces and hence i need to take a mean of the properties of multiple pieces and match it to the row having data about the lot. I was wondering if there is a simple commmand,

Dear R-core There is a different output for the apply function due to the change of unlist as mentioned in the R news. Newly, applying as.factor() (or factor()) in str(dat <- data.frame(x = 1:10, f1 = gl(2,5,labels = c("A", "B")))) (d1 <- apply(dat,2,as.factor)) newly returns a character matrix while in R-2.3.1 the same command resulted in an integer matrix that was

Dear R-list I have a question concerning the argument "adjustSigma" in the function "lme" of the package "nlme". The help page says: "the residual standard error is multiplied by sqrt(nobs/(nobs - npar)), converting it to a REML-like estimate." Having a look into the code I found: stdFixed <- sqrt(diag(as.matrix(object$varFix))) if (object$method

hi list, i have to ask you again, having tried and searched for several days... i want to do a TukeyHSD after an Anova, and want to get the adjusted p-values after the Tukey Correction. i found the p.adjust function, but it can only correct for "holm", "hochberg", bonferroni", but not "Tukey". Is it not possbile to get adjusted p-values after

I like to propose a new loop multi versioning optimization for LICM. For now I kept this for LICM only, but it can be used in multiple places. The main motivation is to allow optimizations stuck because of memory alias dependencies. Most of the time when alias analysis is unsure about memory access and it says may-alias. This un surety from alias analysis restrict some of the memory based

I have some doubts about the validity of my procedure to estimeate linear contrasts ina a factorial design. For sake of semplicity, let's imagine a one way ANOVA with three levels. I am interested to test the significance of the difference between the first and third level (called here contrast C1) and between the first and the seconda level (called here contrast C2). I used the following

hi all, I wish to draw on the same graphic device 3 functions. But i don't want them to be on different graph, i want to compare them on the same I don't need mfrow or mfcol, I need something else... 1 graph on 1 device inside this graph 3 ploted function. I saw something unsing data.frame, but i think it's overkill, and something less complicated must exist, if not why? why not

Hello Could you please suggest a way to find out the r square values for each independent variable while using "lm" for developing a multiple linear regression model. Thank you avneet "I have no data yet. It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories instead of theories to suit facts." ~ Sir Arthur Conan Doyle