/* Exercise 6.5 Statistical Methods in Biology: Design and Analysis of Experiments and Regression by S.J. Welham, S.A. Gezan, S.J. Clark & A. Mead (2014) Chapman & Hall/CRC Press, Boca Raton, Florida. ISBN: 978-1-4398-0878-8 Data from M. Torrance, Rothamsted Research Version 1, 26/10/2014 */ ods graphics on; * Read data - change directory to location of your data file; data PARASITOIDS; infile 'C:\stats4biol\data\PARASITOIDS.DAT' firstobs=2 expandtabs; input DParasitoid Treatment $ OpticalDensity; run; proc print data=PARASITOIDS;run; * Tabulate treatment sample means and variances; proc sort data=PARASITOIDS; by Treatment; run; proc means data=PARASITOIDS mean var; var OpticalDensity; by Treatment; run; * One-way ANOVA of full, untransformed data with Bartlett's test; proc glm data=PARASITOIDS plots=DIAGNOSTICS; class Treatment; model OpticalDensity = Treatment; lsmeans Treatment / stderr cl; means Treatment / hovtest=bartlett; run; * Transform response to log scale; data PARASITOIDS; set PARASITOIDS; LogOpt=log10(OpticalDensity); run; * Remove positive control treatment (level Day0); data PARAS0; set PARASITOIDS; if Treatment='Day0' then delete; run; * One-way ANOVA of reduced, log-transformed data set; proc glm data=PARAS0 plots=DIAGNOSTICS; class Treatment; model LogOpt = Treatment; lsmeans Treatment / stderr cl; means Treatment / hovtest=bartlett; run; * Remove negative control treatment (level Control); data PARAS1; set PARASITOIDS; if Treatment='Control' then delete; run; * Repeat analysis on log scale for reduced data set; proc glm data=PARAS1 plots=DIAGNOSTICS; class Treatment; model LogOpt = Treatment; lsmeans Treatment / stderr cl; means Treatment / hovtest=bartlett lsd; ods output LSMeans=PREDMEANS; run; * Back-Transform treatment means; data PREDMEANS;set PREDMEANS; btmeans=10**(LSMean); run; proc print data=PREDMEANS;run;