Table 4. Scores on five personality factors for all placebo responders (n = 5) and placebo non-responders (n = 9), and differences for placebo responders (n = 5) from scores for placebo non-responders (n = 9).
International Personality Item Pool Factor
Trait score Placebo responders
Trait score Placebo non-responders
Difference from placebo non-responders
Chances effect is clinically positive (neutral/negative)+
Mean (SD)
Mean (SD)
Mean (SD)
95%CI+
Extraversion
89.4 (10.8)
78.8 (8.7)
10.6 (9.8)
-.9 to 22.1
95 (3/2)
Agreeableness
95.4 (12.1)
88.4 (9.8)
7.0 (11.0)
-6.0 to 19.9
80 (12/8)
Conscientiousness
98.0 (13.3)
96.0 (12.3)
2.0 (12.8)
-13.3 to 17.3
48 (25/27)
Neuroticism
60.8 (11.1)
59.7 (10.2)
1.1 (10.7)
-11.7 to 13.9
50 (15/35)
Openness to experience
78.6 (7.7)
72.9 (7.0)
5.7 (7.4)
-3.1 to 14.5
86 (7/6)
smallest worthwhile effect of 0.2 of standard deviation of placebo non-responders for each factor.