Hi all, A beginner's question: I have to analyse univariate, strongly periodic data collected every hour for a period of 1 week and I need to compare 5 different groups for significant differences between them. Is there a better way to do this in R, other than pairwise t-tests of summary statistics? Thanks in advance, Andy -- View this message in context: http://r.789695.n4.nabble.com/periodic-time-series-tp3062866p3062866.html Sent from the R help mailing list archive at Nabble.com.
Hi Andy,
If you could provide a sample data set, it would help others to give a
solution.
I suggest look at the data and select a model, then anova. Take group as one
variable, record time (1 to 24 ) as the second variable and the week day
(Monday to Friday) as the third variable. Then test the interaction between
three variables at first. I hope the following code helps.
df <- data.frame(value = rnorm(24*5*5),
group = rep(1:5,5*24),
time = rep(1:24,each=5),
day =
rep(c("M","T","W","R","F"),each=24))
anova(lm(value ~ group*time*day,data=df),lm(value ~
group*time*day-group:time:day,data=df))
-----
A R learner.
--
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http://r.789695.n4.nabble.com/file/n3063697/sample.xlsx sample.xlsx So, here are some sample data. 1st column is a label for "12 hour long" days 2nd one a time stamp The rest are the actual measured values for 4 different groups. What would be the best model for such periodic data? Thanks, Andy -- View this message in context: http://r.789695.n4.nabble.com/periodic-time-series-tp3062866p3063697.html Sent from the R help mailing list archive at Nabble.com.
----------------------------------------> Date: Sun, 28 Nov 2010 14:48:54 -0800 > From: feki_o at yahoo.co.uk > To: r-help at r-project.org > Subject: [R] periodic time series > > > Hi all, > > A beginner's question: I have to analyse univariate, strongly periodic data > collected every hour for a period of 1 week and I need to compare 5 > different groups for significant differences between them.I don't know if anyone replied but I would mention of course that significant needs to be qualified: statistically significant meaning a difference could be real and clinically significant meaning something anyone cares about.? Presumably you have some features in your data that you care about. You want to design some tests to look at these. If you can describe what you want to do someone here can maybe help your definition a bit and then explain how it could be evaluated in R or some easier approximation etc. Periodic suggests that you expect the samples to differ at different times, this isn't just like sampling a a bunch of points from a box of supposedly identical widgets perhaps. If you have a time series, there are a lot of questions you could want to ask.> > Is there a better way to do this in R, other than pairwise t-tests of > summary statistics? > > Thanks in advance, > Andy > -- > View this message in context: http://r.789695.n4.nabble.com/periodic-time-series-tp3062866p3062866.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.