Dear helpeRs: I am writting you because I have some doubts in relation to the equivalence test. I am interested in compare seed set of treated plants and control plants. I used the tost command in R, and the value of epsilon that I put was the standard deviation of the control sample. In all cases (because this analysis was performed for five populations) I rejected the null hypothesis and these results were in correspondence with those obtained in a prior ANOVA (all null hypothesis were accepted). My doubt is if it is correct to use the standard deviation (or a percentage of it) of the control sample, to define the interval of equivalence. The second question is how I can obtain a parameter t to report in my results. Thank you in advance, Biol. Andrea Cosacov Instituto Multidisciplinario de Biología Vegetal (IMBIV - CONICET) Córdoba - Argentina [[alternative HTML version deleted]]