Table 2.

Placebo Survey ANOVAs main effects and simple contrast analyses for differences between levels of Placebo Acceptability, Positive and Negative Mood, and Trust (VAS = 0–100; n=100)

Main Effect/Contrasts	F	P	ES (ηp²)
Acceptability	F(2.70, 268.12) = 18.80	p < .001^**	.160
Self tx > Standard tx	F(1,99) = 28.06	p < .001^**	.221
Self tx < No Standard tx	F(1,99) = 9.72	p = .002^*	.089
Self tx - Diagnostically	F(1,99) = 1.53	p = .218	.015
Standard tx < No Standard tx	F(1,99) = 53.54	p < .001^**	.351
Standard tx < Diagnostically	F(1,99) = 27.51	p < .001^**	.217
Diagnostically - No Standard tx	F(1,99) = 1.41	p = .237	.014
Likelihood of using placebo by health care providers	F(3.50, 346.39)= 11.24	P < .001^**	.102
Chiropractors > Physicians	F(1,99) = 4.13	P = .067	.040
Chiropractors > Dentists	F(1,99) = 27.54	P < .001^**	.218
Chiropractors > Nurses	F(1,99) = 16.82	P < .001^**	.145
Chiropractors – Physical therapists	F(1,99) = 2.96	P = .089	.029
Chiropractors > Physician Assistants	F(1,99) = 16.58	P < .001^**	.143
Dentists < Physicians	F(1,99) = 22.94	P < .001^**	.186
Dentists < Nurses	F(1,99) = 6.05	P = .016^*	.058
Dentists < Physical therapists	F(1,99) =21.33	P < .001^**	.177
Dentists < Physician Assistants	F(1,99) = 7.39	P = .008^*	.069
Nurses < Physicians	F(1,99) =4.94	P = .029^*	.048
Nurses < Physical therapists	F(1,99) =7.65	P = .007^*	.072
Nurses – Physician Assistants	F(1,99) =.131	P = .718	.001
Physical Therapists – Physicians	F(1,99) = .797	P = .374	.008
Physical Therapists > Physician Assistants	F(1,99) = 8.376	P = .005^*	.078
Physician Assistants < Physicians	F(1,99) = 4.13	P = .045^*	.040
Negative Mood	F(1.81,179.03) = 123.85	p < .001^**	.556
Pain Improves < Pain Worsens	F(1,99) = 185.83	p < .001^**	.652
Pain Improves < No change in Pain	F(1,99) = 95.04	p < .001^**	.490
No Change in Pain < Pain Worsens	F(1,99) = 52.538	p < .001^**	.347
Positive mood	F(1.57,155.71) = 116.70	p < .001^**	.541
Pain Improves > Pain Worsens	F(1,99) = 139.32	p < .001^**	.585
Pain Improves > No Change in Pain	F(1,99) = 140.27	p < .001^**	.586
No change in pain > Pain Worsens	F(1,99) = 5.84	p < .017^*	.056
Trust	F(1.53,151.44) = 125.34	p < .001^**	.559
Pain Improves > Pain Worsens	F(1,99) = 169.98	p < .001^**	.632
Pain Improves > No change in Pain	F(1,99) = 86.78	p < .001^**	.467
No change in pain > Pain Worsens	F(1,99) = 76.44	p < .001^**	.436

Note: F, F Statistic; P, P value; ES, effect size; ηp², partial eta squared;

Indicates significant difference (p < 0.05).

^**

Indicates significant difference (p < 0.001).