Table 1.  Potential for the two- and three-condition experimental design to detect relationships between placebo and experimental conditions, and true baseline values.
Likely outcome 2 condition design 3 condition design
(a)   Exp > Pla Yes Yes
(b)   Exp = Pla Yes Yes
(c)    Pla > Exp Yes Yes
(d)   Exp = Pla = Bas No Yes
(e)   Exp > (Pla = Bas) No Yes
(f)     (Exp = Pla) > Bas No Yes
(g)   Exp > Pla > Bas No Yes
(h)   Pla > (Exp = Bas) No Yes
(i)      Pla > Exp > Bas No Yes
(j)     Exp > (Bas > Pla) No Yes
Abreviations: Bas = Baseline level; Pla = Placebo condition; Exp = experimental condition. The symbol ‘=’ indicates no significant differences between; the symbol ‘>’ indicates that the condition to the left was associated with significantly better performance than the condition to the right.