Dear All: I have a weak background about statistical analysis and need some help me to do analyzes of my data about bacterial count from cecum of cows. I would like to to run the analyses as "Bacterial count values were log transformed, and then a Poisson regression model was fitted using the PROC GENMOD of SAS, with log of bacterial counts as the response variables, and diet (Control, T00, T05 or T10) as the factor explanatory variable, assuming that the random residual variance follows a Poisson distribution. A logistic regression model for binary data (PROC GENMOD of SAS) was used to analyse mortality data". My data is: Additives REP G-negative (log10cfu/g) Coliform (log10cfu/g) Ecoli (log10cfu/g) T00 1 7.85 7.80 6.20 T00 2 7.56 6.95 6.56 T00 3 7.95 7.32 6.55 T00 4 8.02 7.56 6.15 T00 5 7.77 7.87 6.68 T00 6 7.65 7.74 6.32 T05 1 8.68 3.80 4.60 T05 2 8.95 4.15 4.84 T05 3 8.64 4.03 4.56 T05 4 8.72 3.78 4.72 T05 5 8.85 3.68 4.35 T05 6 8.60 3.82 4.60 T10 1 8.36 4.90 4.80 T10 2 8.32 5.20 4.95 T10 3 8.06 5.03 4.65 T10 4 7.98 4.86 5.25 T10 5 8.35 4.93 5.03 T10 6 8.41 5.22 4.75 In a published article, I have seen the result of using GENMOD of SAS as the following table: Table: Caecal bacterial counts (log CFU/g; mean and confidence limits) of animals fed the experimental diets Experimental diets Control T1 T2 T3 P-value E. coli 5.6a (4.12-7.04) 5.4a (3.93-6.81) 3.9ab (2.66-5.10) 3.1b (2.03-4.23) 0.023 Bacteroides spp. 5.0 (3.56-6.34) 4.9 (3.54-6.28) 4.5 (3.22-5.86) 4.2 (2.95-5.49) 0.854 Lactobacillus spp. 3.2a (2.11-4.33) 3.3a (2.18-4.43) 2.2ab (1.29-3.13) 1.6b (0.78-2.32) 0.034 Another friend recommend the use of a Poisson distribution for the GLIMMIX model without telling me how to run it. My questions are: (1) Which one (GENMOD or GLIMMIX) is the best for my data? (2) Please provide me with the code to use in SAS. Best regards, Ahmed
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