Statistical methodology questions are generally off topic here. This list is about R programming. I suggest you post to a statistics site like stats.stackexchange.com instead.
Cheers, Bert Bert Gunter Genentech Nonclinical Biostatistics (650) 467-7374 "Data is not information. Information is not knowledge. And knowledge is certainly not wisdom." Clifford Stoll On Thu, Feb 19, 2015 at 6:47 AM, Jan-Ulrich Kreft <j.kr...@bham.ac.uk> wrote: > Dear list > > I have data from a collaborator who has used DesignExpert to design the > experiment and analyse the data but no longer has access to this software and > does not know exactly what the software did and why. > > So I’m now trying to analyse the data in R but can't quite decide what to do. > > Cell count is the response variable (number of cells attached to a surface > per unit area and time interval, so could be Poisson distributed). > > This cell count depends on whether the surface was oriented upwards or > downwards (categorical - with or against gravity). Some more categorical > variables were also studied such as surface material (glass or polycarbonate, > symbols g and p in the figure) and position in flow cell (inlet or outlet), > but they seem to have no significant effect. > > Cell count also depends on a quantitative variable in a nonlinear manner: the > flow rate with which the cell suspension was pumped along the surface. > > I was wondering which kind of statistical model would be appropriate. I was > first thinking ANCOVA but this seems to be a linear model and treating the > quantitative explanatory variable as covariate when this is actually of > interest. What else could I use? > > Attached a figure showing the means of 4 replicates. > > Many thanks. > > Best wishes, > Jan. > > --- > Dr Jan-Ulrich Kreft > +44 (0)121 41-48851 > School of Biosciences > University of Birmingham, Birmingham, B15 2TT, UK > http://www.tinyurl.com/kreftlab > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
