Results
Data from Davey et al. (2003). The authors investigated how mood and stop rules impact checking thoughts.
ANOVA
ANOVA - checks
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| 95% CI for ω²ₚ | |||||||||||||||||
| Cases | Sum of Squares | df | Mean Square | F | p | ω²ₚ | Lower | Upper | |||||||||
| mood | 34.133 | 2 | 17.067 | 0.683 | 0.509 | 0.000 | 0.000 | 0.000 | |||||||||
| stop_rule | 52.267 | 1 | 52.267 | 2.093 | 0.154 | 0.018 | 0.000 | 0.139 | |||||||||
| mood ✻ stop_rule | 316.933 | 2 | 158.467 | 6.345 | 0.003 | 0.151 | 0.009 | 0.317 | |||||||||
| Residuals | 1348.600 | 54 | 24.974 | ||||||||||||||
| Note. Type III Sum of Squares | |||||||||||||||||
The resulting output can be interpreted as follows. The main effect of mood was not significant, F(2, 54) = 0.68, p = .51, indicating that the number of checks (when we ignore the stop rule adopted) was roughly the same regardless of whether the person was in a positive, negative or neutral mood.
Similarly, the main effect of stop rule was not significant, F(1, 54) = 2.09, p = .15, indicating that the number of checks (when we ignore the mood induced) was roughly the same regardless of whether the person used an ‘as many as can’ or a ‘feel like continuing’ stop rule.
The mood × stop rule interaction was significant, F(2, 54) = 6.35, p = .003, indicating that the mood combined with the stop rule significantly affected checking behaviour. To dissect the interaction effect, we can look at a descriptives plot, or conditional post hoc tests.
Descriptives
Descriptives plots
The error bar plot shows that when in a negative mood people performed more checks when using an *as many as can* stop rule than when using a *feel like continuing* stop rule. In a positive mood the opposite was true, and in neutral moods the number of checks was very similar in the two stop rule conditions, just as Davey et al. predicted. The wide error bars indicate some uncertainty about these differences though, so we could investige this further by conducting a conditional post hoc test on the interaction effect. The results below show that the difference between the stop rules is only statistically significant for people with a positive mood.
Post Hoc Tests
Standard (HSD)
Post Hoc Comparisons - mood ✻ stop_rule - Conditional on mood
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| mood | Mean Difference | SE | df | t | ptukey | ||||||||||
| Neutral | As many as you can | Feel like continuing | -1.200 | 2.235 | 54 | -0.537 | 0.594 | ||||||||
| Negative | Feel like continuing | 3.400 | 2.235 | 54 | 1.521 | 0.134 | |||||||||
| Positive | Feel like continuing | -7.800 | 2.235 | 54 | -3.490 | < .001 | |||||||||
Post Hoc Comparisons - mood ✻ stop_rule - Conditional on stop_rule
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| stop_rule | Mean Difference | SE | df | t | ptukey | ||||||||||
| As many as you can | Neutral | Negative | -3.900 | 2.235 | 54 | -1.745 | 0.198 | ||||||||
| Positive | 1.700 | 2.235 | 54 | 0.761 | 0.729 | ||||||||||
| Negative | Positive | 5.600 | 2.235 | 54 | 2.506 | 0.040 | |||||||||
| Feel like continuing | Neutral | Negative | 0.700 | 2.235 | 54 | 0.313 | 0.947 | ||||||||
| Positive | -4.900 | 2.235 | 54 | -2.192 | 0.082 | ||||||||||
| Negative | Positive | -5.600 | 2.235 | 54 | -2.506 | 0.040 | |||||||||
| Note. P-value adjusted for comparing a family of 3 estimates. | |||||||||||||||
Raincloud Plots
Raincloud Plots
checks
