[R] How to compute time interval?

time1 = 2008-03-09 time2 = 2010-9-10 How to compute how many years between time1 and time2? Thanks! best [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read

Re: [R] How to compute time interval?

t2-t1 is ok,but only can getTime difference of 786 days,but I wanna get the 786 only.How can I do then? Thanks! 2011/11/11 Lao Meng laomen...@gmail.com time1 = 2008-03-09 time2 = 2010-9-10 How to compute how many years between time1 and time2? Thanks! best [[alternative HTML

Re: [R] How to compute time interval?

as.numeric() is work Settled! 2011/11/11 Lao Meng laomen...@gmail.com t2-t1 is ok,but only can getTime difference of 786 days,but I wanna get the 786 only.How can I do then? Thanks! 2011/11/11 Lao Meng laomen...@gmail.com time1 = 2008-03-09 time2 = 2010-9-10 How to compute how many

[R] How to get the descriptive statistic of the whole dataframe?

Hi all: If I have a dataframe of N columns.If I wanna get the min(or max,or mean...etc)of the whole dataframe,how to do it quickly? What I can do is only: min(data[,1:ncol(data)]) Any other suggestion? Thanks! best [[alternative HTML version deleted]]

Re: [R] a question about lm on t-test.

:57, schrieb Lao Meng: Thanks Eik. As to your words:The intercept in lm is tested against 0 (one sample t-test) So, I perform the following test: t.test(extra[group==1],mu=0) Since goup1 is regarded as reference,I do the 1-sample ttest based on group1's mean vs 0. But the result

Re: [R] how to get the result in short cut manner?

Yes, you remind me of this! Thanks! 2011/8/16 Eik Vettorazzi e.vettora...@uke.uni-hamburg.de Hi Lao, you tried to reinvent the wheel. Have a look at ?tapply tapply(sleep$extra,sleep$group,mean) Cheers Am 16.08.2011 09:41, schrieb Lao Meng: Hi all: My data:data(sleep) If I wanna

Re: [R] a question about lm on t-test.

- number of parameters) degrees of freedom. cc-s1$coef[(Intercept),1:2] 2*(1-pt(cc[1]/cc[2],df=18)) hth. Am 16.08.2011 07:25, schrieb Lao Meng: Hi all: I have a question about lm on t-test. data(sleep) I wanna perform t-test to test the difference between the 2 groups: I

Re: [R] a question about lm on t-test.

...1k --- Sent from my phone. Please excuse my brevity. Lao Meng laomen...@gmail.com wrote: The mean of group1 is 0.75,just the same as intercept. Acturally,R treated group1 as reference,so intercept is just group1

[R] how to get the result in short cut manner?

Hi all: My data:data(sleep) If I wanna calculate each group's extra,what I can do is: #method1 attach(sleep) mean(extra[group==1]) mean(extra[group==1]) #method2 result-matrix(,0,2) g-split(sleep,sleep$group) for(i in 1:length(g)) {

Re: [R] how to get the result in short cut manner?

Sorry,I miss a word:If I wanna calculate each group's mean extra 2011/8/16 Lao Meng laomen...@gmail.com Hi all: My data:data(sleep) If I wanna calculate each group's extra,what I can do is: #method1 attach(sleep) mean(extra[group==1]) mean(extra[group==1]) #method2 result-matrix

[R] a question about lm on t-test.

Hi all: I have a question about lm on t-test. data(sleep) I wanna perform t-test to test the difference between the 2 groups: I can use: t.test(extra~group) The t.test result shows that:t = -1.8608; mean1=0.75,mean2=2.33 But I still wanna use: summary(lm(extra~group)) Intercept=0.75,which

Re: [R] a question about lm on t-test.

#. with /Software/Embedded Controllers) .OO#. .OO#. rocks...1k --- Sent from my phone. Please excuse my brevity. Lao Meng laomen...@gmail.com wrote: Hi all: I have a question about lm on t-test. data(sleep) I wanna perform t-test

Re: [R] a question about glht function

Here's another question: What's kind of difference does glht tests? In other words, If I get 4 intercepts and 4 slopes for all levels of GROUP,then glht tests for the difference of the 4 intercepts or 4 slopes,or something else? Thanks. 2011/7/27 Lao Meng laomen...@gmail.com Yes. According

[R] a question about glht function

Hi all: There's a question about glht function. My data:data_ori,which inclue CD4, GROUP,time. f_GROUP-factor(data_ori$GROUP) f_GROUP is a factor of 3 levels(0,1,2,3) result - lme(sqrt(CD4) ~ f_GROUP*time ,random = ~time|ID,data=data_ori) glht(result, linfct = mcp(f_GROUP=Tukey) ) Error in

Re: [R] a question about glht function

Yes. According to your suggestion,I modified my code.It works well. Thanks you very much. My best. 2011/7/26 Peter Ehlers ehl...@ucalgary.ca On 2011-07-26 00:16, Lao Meng wrote: Hi all: There's a question about glht function. My data:data_ori,which inclue CD4, GROUP,time. f_GROUP

[R] question about linear mixed model

Hi all: I have a question about linear mixed model. my linear mixed model with randomized slope and intercept with interaction of time and group(g1,g2,g3): model- glmmPQL(log10(CD4) ~ time + factor(group)+ time:factor(group), random = ~time|id) What I get is only the main and interaction of time

[R] How to compare ratio from multiple groups?

If I have 3 groups,and for each group,I get the ratio(e.g. incidence rate). Now I wanna compare 3 ratio pairwise,and get the corresponding p values,i.e: group1 vs group2 ,p value=? group1 vs group3 ,p value=? group2 vs group3 ,p value=? Which statistical test should be used? Thanks a lot for

[R] About the covariant

Hi all,I have some questions about the covariants of regression. My target: To explore the trend of CD4 level through a period of time. Response variable: CD4 count Explanatory variable:time Also, the demology information is available,such as gender,occupation,income level... Q1,Are these

Re: [R] About the covariant

(High). 2011/6/28 David Winsemius dwinsem...@comcast.net On Jun 27, 2011, at 10:02 PM, Lao Meng wrote: Hi all,I have some questions about the covariants of regression. My target: To explore the trend of CD4 level through a period of time. Response variable: CD4 count Explanatory

Re: [R] A better way to do this

You may try xyplot 2011/5/20 1Rnwb sbpuro...@gmail.com Hello gurus, I have a dataframe containing two groups viz., 'control' and 'case', each of these groups contains longitudinal data for 100 subjects. I have to plot all these subjects on a single chart and then put a regression line

[R] competitive risk model

Hi all: Which function or package can perform competitive risk model? Thanks a lot! My best [[alternative HTML version deleted]] __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting

Re: [R] is this an ANOVA ?

You may try the following to perform anova: anova(lm(y~x)) or summary(aov(y~x)) 2011/4/13 Ubuntu Diego ubuntu.di...@gmail.com Hi all, I have a very easy questions (I hope). I had measure a property of plants, growing in three different substrates (A, B and C). The rest of the

Re: [R] qcc.overdispersion-test

hi: Another question abour overdispersion test. I wanna make sure that: if p value0.05,then the data is NOT overdispersion; if p value=0.05,then the data IS overdispersion. I'm not sure whether it's true,just get the above conclusion from simulated data. Thanks for your help. 2011/4/2

[R] Sample size of longitudinal and skewed data

Hi all: I have a question about the sample size calculation. It's a pilot study,which includes 2 groups(low,high),3 time point(3,6,9 monthes).Each person has 3 results which according to the 3 time points.So it's a longitudinal study. I want to calculate the minimum sample size from the pilot

[R] sample size of 2 groups of skewed data

Hi all: I have a question on sample size calculation of 2 groups of data. If 2 groups of data are all normal distribution, then I can use the function n.indep.t.test.eq from samplesize package.But if 2 groups of data are all skewed distribution, but not normal distribution,how can I calculate the

Re: [R] Boxplot problem

No,even there's only one observation,boxplot can still be drawn. x-1 boxplot(x) or x-1:3 boxplot(x) ... 2011/3/9 Dennis Murphy djmu...@gmail.com Hi: A box plot is based on a five number summary, so you need at a minimum five observations (and preferably at least twice that) to make a

Re: [R] regression with categorical nuisance variable

You may try analysis of covariance. But,as you sayThere are no gender differences in age ,then why not combine 2 gender's age and ignore the gender? 2011/3/1 Jonathan DuBois jonathan.m.dub...@gmail.com Hi, I am new to R, so I am unsure of the formula to set up this analysis. I would like to

Re: [R] How to change dataframe to tables

Thanks! It works well. 2011/2/18 Dimitris Rizopoulos d.rizopou...@erasmusmc.nl say, 'Dat' is your data frame, then one way to do it is: with(Dat, tapply(freq, list(hair, eye, sex), c)) I hope it helps. Best, Dimitris On 2/18/2011 8:50 AM, Lao Meng wrote: The data

Re: [R] How to change dataframe to tables

Thanks! It works well. 2011/2/18 Henrique Dallazuanna www...@gmail.com Try this: xtabs(Freq ~ Hair + Eye + Sex, Dat) Using Dimitri's Dat example. On Fri, Feb 18, 2011 at 5:50 AM, Lao Meng laomen...@gmail.com wrote: The data is in the attachment. What I wanna get is: , , Sex

Re: [R] How to change dataframe to tables

Well,it's my daily work on duty,not homework:) 2011/2/18 Dennis Murphy djmu...@gmail.com This is a built-in dataset in R - see ?HairEyeColor and str() it. I smell homework... Dennis On Thu, Feb 17, 2011 at 11:50 PM, Lao Meng laomen...@gmail.com wrote: The data is in the attachment

[R] How to change dataframe to tables

The data is in the attachment. What I wanna get is: , , Sex = Male Eye HairBrown Blue Hazel Green Black32 1110 3 Brown53 502515 Red 10 10 7 7 Blond 3 30 5 8 , , Sex = Female Eye HairBrown Blue Hazel Green

[R] 3 questions about the poisson regression of contingency table

Hi all: I have 3 questions about the poisson regression of contingency table. Q1¡¢How to understand the independent poisson processas many books or paper mentioned? For instance: Table1 --- treat canernon-cancersum

[R] 3 questions about the poisson regression of contingency table

Hi all: I have 3 questions about the poisson regression of contingency table. Q1¡¢How to understand the independent poisson processas many books or paper mentioned? For instance: Table1 --- treat canernon-cancersum

[R] question about result of loglinear analysis

Hi all: Here's a question about result of loglinear analysis. There're 2 factors:area and nation.The raw data is in the attachment. I fit the saturated model of loglinear with the command: glm_sat-glm(fre~area*nation, family=poisson, data=data_Analysis) After that,I extract the coefficients:

[R] Fwd: question about result of loglinear analysis

-- Forwarded message -- From: Lao Meng laomen...@gmail.com Date: 2011/1/19 Subject: Re: [R] question about result of loglinear analysis To: David Winsemius dwinsem...@comcast.net My command and result are : result_sat-summary(glm_sat) result_coe-result_sat$coefficients

[R] How to find out the trend during a time period?

Hi all: I have a dataset which contains two variables: Y and time y-c(228,189,232,198,252,315) time-2003:2008 How can I find out the trend(increase/decrease) of y along the time period? If I use: lm(y~time) The lm command treats time as natural number,but not date. So maybe lm isn't