Hi Bill: Without having more information about the design (specific hypothesis) and given the temporal replication, you might wish to consider using occupancy models (http://www.uvm.edu/envnr/vtcfwru/spreadsheets/occupancy/occupancy.htm) rather than repeated measures. These types of models can also be applied for interactions between species (see Chapter 8; Occupancy Estimation and Modeling. MacKenzie et. al. 2006. Academic Press).
Brian Campbell > Date: Mon, 30 Jun 2008 13:43:00 -0500 > From: [EMAIL PROTECTED] > Subject: [ECOLOG-L] Statistical advice > To: [email protected] > > Good afternoon all: > > I am looking for some statistical advice, in a situation that has me > temporarily stumped. > > We have data which includes a categorical predictor variable (a landscape > attribute, habitat patch size), two continuous dependent variables (measures > of plant and rodent abundance), and many years of observations. Experimental > hypotheses involve the question of how patch size affects organism abundance, > and also about correlations between plant and rodent abundance. > > This seems to be set up exactly for the repeated measures ANOVA function in > SPSS within the GLM section, only no information is given in the printout > about associations between the dependent variables. What would you recommend > we do to formally investigate the relations between plant and rodent > abundance (the dependent variables), in the light of time and patch size? So > far we can run a RMANOVA to investigate time and patch size, and then to run > separate analyses (e.g. correlations within each year) to look at the > association between plant and rodent abundance, but there may be a more > holistic way to do this. > > Thanks for any advice you can give. > > Bill Cook > > William M. Cook > Assistant Professor > Department of Biological Sciences > St. Cloud State University > 720 4th Avenue South > St. Cloud, MN 56301 USA > Phone: (320) 308-2019 > E-mail: [EMAIL PROTECTED] _________________________________________________________________ Send a smile, make someone laugh, have some fun! Start now! http://www.freemessengeremoticons.ca/?icid=EMENCA122
