[R] multilevel models and sample size
It is not a pure R question,but I hope some one can give me advices. I want to use analysis my data with the multilevel model.The data has 2 levels the second level has 52 units and each second level unit has 19-23 units.I think the sample size is quite small,but just now I can't make the sample size much bigger.So I want to ask if I use the multilevel model to analysis the data set,will it be acceptable? or unacceptable because of the small sample size? Thank you very much! ronggui 2005-11-28 -- Deparment of Sociology Fudan University My new mail addres is [EMAIL PROTECTED] Blog:http://sociology.yculblog.com __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] multilevel models and sample size
All models are wrong, but some are useful. --George Box I do not understand what you mean by acceptable, nor levels nor units. Specifying your model would help clarify things, I think. If by levels you mean number of different values of a random factor, than 2 levels is unlikely to tell you much useful about the variability of that factor. On the other hand, 50 values might be. Depends on the model,the data, and the scientific objectives, none of which you have stated clearly enough for me to understand, anyway. -- Bert -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ronggui Sent: Sunday, November 27, 2005 9:34 AM To: r-help@stat.math.ethz.ch Subject: [R] multilevel models and sample size It is not a pure R question,but I hope some one can give me advices. I want to use analysis my data with the multilevel model.The data has 2 levels the second level has 52 units and each second level unit has 19-23 units.I think the sample size is quite small,but just now I can't make the sample size much bigger.So I want to ask if I use the multilevel model to analysis the data set,will it be acceptable? or unacceptable because of the small sample size? Thank you very much! ronggui 2005-11-28 -- Deparment of Sociology Fudan University My new mail addres is [EMAIL PROTECTED] Blog:http://sociology.yculblog.com __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] multilevel models and sample size
ronggui wrote: It is not a pure R question,but I hope some one can give me advices. I want to use analysis my data with the multilevel model.The data has 2 levels the second level has 52 units and each second level unit has 19-23 units.I think the sample size is quite small,but just now I can't make the sample size much bigger.So I want to ask if I use the multilevel model to analysis the data set,will it be acceptable? or unacceptable because of the small sample size? This kind of question I usually try to answer by simulation, which is very easy in R. Kjetil Thank you very much! ronggui 2005-11-28 -- Deparment of Sociology Fudan University My new mail addres is [EMAIL PROTECTED] Blog:http://sociology.yculblog.com __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Re: [R] multilevel models and sample size
On Sun, 27 Nov 2005, Berton Gunter wrote: All models are wrong, but some are useful. --George Box I do not understand what you mean by acceptable, nor levels nor units. Specifying your model would help clarify things, I think. If by levels you mean number of different values of a random factor, than 2 levels is unlikely to tell you much useful about the variability of that factor. On the other hand, 50 values might be. Depends on the model,the data, and the scientific objectives, none of which you have stated clearly enough for me to understand, anyway. My guess is that he means this is a tested design with e.g. 52 classes containing 19-23 pupils each. (It always helps to state the real problem!) If so, this is quite a large problem for multilevel models. The classical nested designs for measurement errors typically have two replications at the lowest level - you get an idea of the variability from the many differences between matched pairs. Of course the homogeneity assumptions have to be approximately true. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of ronggui Sent: Sunday, November 27, 2005 9:34 AM To: r-help@stat.math.ethz.ch Subject: [R] multilevel models and sample size It is not a pure R question,but I hope some one can give me advices. I want to use analysis my data with the multilevel model.The data has 2 levels the second level has 52 units and each second level unit has 19-23 units.I think the sample size is quite small,but just now I can't make the sample size much bigger.So I want to ask if I use the multilevel model to analysis the data set,will it be acceptable? or unacceptable because of the small sample size? -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
