```Date: Mon, 1 Feb 2010 11:14:11 -0800 Reply-To: tarpon Sender: "SAS(r) Discussion" From: tarpon Organization: http://groups.google.com Subject: nested design ?'s Comments: To: sas-l@uga.edu Content-Type: text/plain; charset=ISO-8859-1 hey guys: i collected larval fish at a few different sampling sites a few hours apart--morning and afternoon-- (~ 4 hours) for a our month period to determine if the abundance measurements changed during the day. i have written the following code: of course, i'm willing to listen to crictism of code and what not......thanks in advance for an input proc glm data=larval_fish; class tod_id site_id julian_date ; model density= site_id julian_date(site_id) tod_id (site_id*julian_date); means tod_id(site_id*julian_date); run; quit; where site_id = specific sampling site tod_id= morning or afternoon sample julian date=1 to 365 (starting with january 1st as "1" and december 31st as "365"---for those of you who haven't see this before....) my output.....i'm trying to determine the proper df for the interactions (see below) to report...i understand that densities at sampling sites are statistically dissimilar (F=9.8, p =<.0001), that density at a specific site is dissimliar between sample dates (julian date) (F=3.79, p= <.0001) and the last interaction, and most important to me, that a comparsion of fish density between the morning and afternoon at a specific sample site on the same date is dissimliar (F=2.1, p = .0014) The GLM Procedure Dependent Variable: density Sum of Source DF Squares Mean Square F Value Pr > F Model 74 72.8700523 0.9847304 3.92 <.0001 Error 121 30.3659822 0.2509585 Corrected Total 195 103.2360345 R-Square Coeff Var Root MSE density Mean 0.705859 123.7053 0.500958 0.404960 Source DF Type I SS Mean Square F Value Pr > F site_id 10 26.91048951 2.69104895 10.72 <.0001 julian_date(site_id) 27 26.48996349 0.98110976 3.91 <.0001 tod_i(site_i*julian) 37 19.46959932 0.52620539 2.10 0.0014 Source DF Type III SS Mean Square F Value Pr > F site_id 10 24.58203525 2.45820352 9.80 <.0001 julian_date(site_id) 27 25.64715356 0.94989458 3.79 <.0001 tod_i(site_i*julian) 37 19.46959932 0.52620539 2.10 0.0014 ```

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