search for: aov

Hello, I have a simple question about using the aov function syntax (ie. * + or :) for the interaction of 2 factors. I have read the help files, and researched other sites, and have included my source files. My goal is to measure the signifigance of the interaction between population and condition (aka. population:condition). I can't seem to fig...

Hi, I've done a repeated ANOVA looking as follows: model<-aov(y~a*b*c+Error(d)) Now I want to get rid of some or all of the interactions. But neither AIC nor anova work. What is the appropriate function to test my model?

Hi, I have a question of aov. e.g. aov.ex = aov(x~y) summary(aov.ex) The aov summary will print to the screen. How can I extract the aov result, in particular the values of Pr(>F) and F value into a vector so that I can use them for other use? Thanks. -- Waverley @ Palo Alto

Greetings to all, This is my model: aov.fit<-aov(Y~A+B+C+D+E+A:C+A:E) In summary(aov.fit) all F values are comptuted by eg MS(A)/MS(Residuals). This is not correct (or what I want), except for F(B) and F(A:E). I suppose P values are not correct either. Is it possible with aov to define the way F computations will be done? I 'd l...

Dear R Users, I want to write a function that applies to the dataframe and variables that were used in a previous call to lm or aov. In order to do this, I need to write a function that applies to the output of lm or aov, and yields the names of the dataframe and variables that were used in the lm or aov analysis. For example, suppose that I give the command: aov.out <- aov( Rt ~ Vis*Cmplx*Isi, data = Rt.data) I want t...

Dear listmembers, I would like to define a class with a slot that takes either an object of class aov or NULL. I have been reading "S4 Classes in 15 pages more or less" and "Lecture: S4 classes and methods" #First I tried with list and NULL setClass(listOrNULL") setIs("list", "listOrNULL") setIs("NULL", "listOrNULL") #doesn't wo...

Dear R-Community! The example "oats" in MASS (2nd edition, 10.3, p.309) is calculated for aov and lme without interaction term and the results are the same. But I have problems to reproduce the example aov with interaction in MASS (10.2, p.301) with lme. Here the script: library(MASS) library(nlme) options(contrasts = c("contr.treatment", "contr.poly")) # aov: Y ~ N +...

...at both: (1) the between target variance, and (2) the within target and between query variance contribute in large part to the overall variance. Thus, differences between the different levels of "method", should be emphasised by blocking on "target" or "query". > m.aov = aov(formula = response ~ method + Error(target/query), data = d) > summary( m.aov ) Error: target Df Sum Sq Mean Sq F value Pr(>F) Residuals 27 18.8539 0.6983 Error: target:query Df Sum Sq Mean Sq F value Pr(>F) Residuals 56 3.15927 0.05642 Error: Within...

Dear Madame, Dear Sir, I am able to obtain the coefficients from a 'summary' of 'lm', but NOT from a 'summary' of 'aov'. The following example shows my steps. ## Initialize rm(list = ls()) # remove (almost) everything in the working environment utils::data(npk, package="MASS") # get data model <- yield ~ block + N*P*K ## Using lm npk.lm <- lm(model, npk) ( s.npk.lm <- summary(npk.lm) ) ......

...<- data.frame(y=rnorm(12), a=factor(rep(letters[1:4],3))) > tmp y a 1 -0.60866099 a 2 0.55500538 b 3 0.12231693 c 4 -0.24613790 d 5 -0.09253593 a 6 -1.54652581 b 7 0.17204210 c 8 -1.22778942 d 9 1.22151194 a 10 -0.43982577 b 11 -1.25444287 c 12 -0.97251060 d > tmp.aov <- aov(y ~ a, data=tmp) > summary(tmp.aov) Df Sum Sq Mean Sq F value Pr(>F) a 3 1.5220 0.5073 0.6973 0.5794 Residuals 8 5.8209 0.7276 > dump("tmp.aov") > rm(tmp.aov) > source("dumpdata.R") > ls() [1] "tmp&quot...

...riate post, but I've found a bug in proj I'd like to track down a bit further before making a formal bug report. The example below shows the problem, if you change the rownames proj fails. The problem seems to be that there is a mismatch in the rownames in the qr objects constructed by aov and the rownames that proj is expecting them to have. My question is - should I be trying to 1. correct the rownames of the qr object that aov makes, or is this likely to create other problems 2. change the way proj does its subsetting? Or is this something that is likely to be quite tricky an...

Hi everyone, I'm having a little trouble with working out what formula is better to use for a repeated measures two way anova. I have two factors, L (five levels) and T (two levels). L and T are both crossed factors (all participants do all combinations). So, I do: summary(aov(dat~L*T+Error(participant/(L*T)),data=dat4)) But get different results with: anova(lme(dat~L*T,random=~1|participant,data=dat4)). Rather, the lme results are the same as those with the formula summary(aov(dat~L*T+Error(participant),data=dat4)) I know most people advocate the use of lme r...

...at the problem will be fixed in a future release of the lme4 package? Using simulated data for a quite standard mixed-model anova (a balanced two-way design; see code for the function SimMixed pasted below), I compared the output of lmer, for three slightly different models, with the output of aov. For an example where there is no fixed treatment effect (null hypothesis is true), with 4 blocks, 2 treatments, and 40 observations per treatment-block combination, I find that lmer gives more statistical significances than it should, whereas aov does not have this problem. An example of outpu...

Dear all, I'm trying to access the Sums of Squares resulting from a summary(aov(....)) so I can use them in a function. Is there an easy way to access these? The structure of a summary.aov object is something like this: > str(summary(fhc.aov)) List of 5 $ Error: PPNR :List of 1 ..$ :Classes anova and `data.frame': 1 obs. of 5 variables: .. ..$ Df :...

R developers, I have a first attempt to make an aov function. Eventually I want to build in Error() structure, but first I am trying to get this presentable for balanced data with only a single stratum, just using residual error. I am following R. M. Heiberger's Computation for the Analysis of Designed Experiments, Wiley (1989)...

...c( lh_cueL, lh_cueR, rh_cueL, rh_cueR ) cuelabels <- c("CueLeft", "CueRight") hemlabels <- c("LH", "RH") roiDataframe <- data.frame( roi=roiValues, Subject=gl(8,1,32,subjectlabels), Hemisphere=gl(2,16,32,hemlabels), Cue=gl(2,8,32,cuelabels) ) roi.aov <- aov(roi ~ (Cue*Hemisphere) + Error(Subject/(Cue*Hemisphere)), data=roiDataframe) print(summary(roi.aov)) ######################################## I've tried to create a contrast matrix like this: cm <- contrasts(roiDataframe$Cue) which gives the main effect contrasts for the Cue f...

<ripley at stats.ox.ac.uk> wrote: > Hint 2: in the absence of balance, ...., and lme can do that Would it be possible to make aov like wrappers to the various special lm variants allowing for a uniform syntax for anova? aov(resp~f1*f2+Error(S/(f1*f2))) ## uses lm aov.lme(resp~f1*f2+Error(S/(f1*f2))) ## uses lme aov.rlm(resp~f1*f2+Error(S/(f1*f2))) ## uses rlm ... I'd do it, but I do not nearly understand enough of the...

I've recently run into the problem of using aov with nested factors, and wanting to get the type II and III sums of squares. Normally Anova from the car package would do fine, but it doesn't like having an Error included, so my.aov <-aov(Response ~ Treatment + Error(Treatment:Replicate)) Anova(my.aov, type="II") yields Er...

I performed an aov() analysis and got the following results: Df Sum Sq Mean Sq F value Pr(>F) block 1 0.0040 0.0040 0.3282 0.5672 Residuals 269 3.2766 0.0122 Can anyone tell me how to extract the F value column and Pr(>F) column from the summary output of aov analysis? Many thanks in advan...

...that even I could understand... ;-) Now, I want to calculate a post-hoc test following up a within-subjects ANOVA. The dv is reaction time (RT), there is a 3-level Condition factor (Cond; within-subjects), a number of subjects (Subj), and the dataframe is called WMU3C. The model is > RT.aov <- aov(RT~Cond + Error(Subj/Cond), WMU3C) I understand that TukeyHSD only works with an aov object, but that RT.aov is an aovlist object. > class(RT.aov) [1] "aovlist" "listof" I've tried to work around it using the "maiz" example in the MMC documentati...