Table 5.
Deception, trust, and negative mood repeated measures (2 × 3) ANOVAs
| Factors/Contrast | F | P | ES |
|---|---|---|---|
| Deception | |||
| Instructions | F(1, 56) = 66.85 | <.001** | ηp2 = .544 |
| Enhanced placebo > RA | - | <.001** | ηp2 = .544 |
| Tx Outcome | F(2, 112) = 2.69 | .072 | ηp2 = .046 |
| Instruction x Tx Outcome | F(2, 122) = 1.36 | .260 | ηp2 = .024 |
| Trust in Healthcare Provider | |||
| Instructions | F(1, 56) = 33.97 | <.001** | ηp2 = .378 |
| RA > Enhanced placebo | - | <.001** | ηp2 = .378 |
| Tx Outcome | F(2, 112) = 7.86 | .001* | ηp2 = .123 |
| Improves > Worsens | - | .001* | ηp2 = .180 |
| No Change > Worsens | - | <.001** | ηp2 = .204 |
| Improves – No Change | - | .823 | ηp2 = .001 |
| Instructions x Tx Outcome | F(1.71, 95.81) = 2.93 | .066 | ηp2 = .050 |
| Negative Mood | |||
| Instructions | F(1, 56) = 40.80 | <.001** | ηp2 = .421 |
| Enhanced placebo > RA | - | <.001** | ηp2 = .421 |
| Tx Outcome | F(2, 112) = 42.08 | <.001** | ηp2 = .429 |
| Worsens > Improves | - | <.001** | ηp2 = .546 |
| Worsens > No Change | - | <.001** | ηp2 = .324 |
| No Change > Improves | - | <.001** | ηp2 = .275 |
| Instructions x Tx Outcome | F(2, 112) = 3.27 | .042 | ηp2 = .055 |
| Enhanced Placebo | |||
| Improves < No Change | - | <.001** | d= .602 |
| Improves < Worsens | - | <.001** | d= 1.213 |
| No Change < Worsens | - | .001* | d= .564 |
| Random Assignment | |||
| Improves – No Change | - | .190 | d= .286 |
| Improves < Worsens | - | <.001** | d= .651 |
| No Change < Worsens | - | .014* | d= .393 |
| Pain Improves | |||
| Enhanced Placebo > RA | - | .006* | d= .502 |
| No Change in Pain | |||
| Enhanced Placebo > RA | - | <.001** | d= .845 |
| Pain Worsens | |||
| Enhanced Placebo > RA | - | <.001** | d= .629 |
Note: RA, Random assignment instructions; F, F statistics; P, p value; ηp2, partial eta squared effects size; d = Cohen’s d effect size;
*
Indicates significant deviation (p < .05);
**
Indicates significant deviation (p < .001).