I want to compare the changes in blood pressure occurring following 2 anesthetic drugs. So in a crossover design, each participant comes for 3 sessions and gets either of placebo, drug A or drug B on 3 separate days. The data collected is 'pre drug BP' on each of 3 sessions and 'post drug BP' for each participant.

How should I statistically compare them (I will be using SPSS).

  • 1
    $\begingroup$ What is your question? $\endgroup$
    – Russ Lenth
    Oct 11, 2014 at 0:12
  • $\begingroup$ Please add to your original question by clicking the gray "edit" at its bottom left. Please add more detail about your setup & data. Your setup / comment doesn't make sense to me. Did you give three drug treatments in a row? $\endgroup$ Oct 11, 2014 at 1:31
  • $\begingroup$ Are you using diastolic BP, systolic BP, both, or mean BP (defined as [2*diastolic + systolic]/3)? $\endgroup$ Oct 11, 2014 at 13:39
  • $\begingroup$ Hi, SBP and DBP , both $\endgroup$
    – Stanley
    Oct 11, 2014 at 14:15

1 Answer 1


If truly within subjects, so a participant gets drug A on day 1 and placebo on day 2 and (etc..) (so NOT pp1: day1 drugA day2 drugA day3 drugA vs pp2: day1 drugB day2 drugB day3 drugB etc) Then you can use One Way repeated Measure ANOVA (if KS's p < .05 then Friedman's ANOVA)


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