Increased Effect Sizes in a Mindfulness- and Yoga-Based Intervention After Adjusting for Response Shift with...

Area of Science:

• Psychology
• Mind-Body Interventions
• Quantitative Research Methods

Background:

• Response shift, a change in internal standards, can affect self-reported outcomes over time.
• Mindfulness and yoga interventions aim to improve well-being, but their effects may be influenced by response shift.
• Accurately measuring intervention effects requires accounting for potential response shifts.

Purpose of the Study:

• To evaluate the then-test's effectiveness in detecting response shift in student musicians undergoing a mindfulness and yoga intervention.
• To determine how adjusting for response shift impacts the calculated effect sizes of the intervention.
• To explore the role of response shift in self-reported mindfulness.

Main Methods:

• Thirty-one student musicians completed the Five Facet Mindfulness Questionnaire (FFMQ) at two time points during an intervention.
• A then-test approach was used, asking participants to retrospectively rate their mindfulness at the first time point.
• Paired t-tests and Hedges' g effect sizes were calculated to assess response shift and intervention effects, both before and after adjustment.

Main Results:

• Significant response shift was observed for the FFMQ Observe subscale and total scale.
• Adjusting for response shift resulted in larger and significant effect sizes across all FFMQ subscales and the total scale.
• The adjusted effect sizes were generally greater than the conventional effect sizes, which were only significant for three subscales and the total scale.

Conclusions:

• The then-test is a valuable tool for quantifying response shift in intervention studies.
• Adjusting for response shift can reveal larger and more robust intervention effects.
• Mindfulness and yoga interventions may have a greater impact than initially measured when response shift is considered.