Mindfulness programmes: reading the evidence

Step 1 Warm-up recall

From Module 1: how is Cohen’s d calculated, and which labels are used for 0.2, 0.5 and 0.8?

Your answer

Private: nothing you type here is sent or stored.

Step 2 Learning goal

By the end of this lesson you can:

• describe what a meta-analysis pools and what Goyal and colleagues (2014) found (Foundation);
• read an effect size with its 95% confidence interval (Core);
• explain why “moderate” and “low” evidence are not the same as “works” and “does not work” (Core).

Step 3 A familiar example

One trial of a new teaching method might look good by luck. Ten trials that point the same way are harder to dismiss. A meta-analysis gathers many trials and combines them.

Step 4 Clear explanation

A meta-analysis pools the results of many studies on one question. Goyal and colleagues (2014) reviewed meditation programmes for psychological stress and well-being and included 47 trials with 3,515 participants. Looking at mindfulness meditation programmes, they rated the strength of the evidence:

A confidence interval gives a range of values compatible with the data. The depression interval runs from 0.00 to 0.59, so its lower end touches zero: the data are compatible with anything from no effect to a moderate one. The anxiety interval, 0.12 to 0.64, sits entirely above zero, but its width shows the size is uncertain.

“Low” evidence means the evidence base is thin or inconsistent, not that the practice has been shown to fail. “Moderate” does not mean large. And “meditation programme” means an organised course, usually over weeks, not a single quiet minute.

Step 5 Worked example (4 marks)

A trial reports d = 0.25 with a 95% confidence interval of −0.05 to 0.55.

1. Width = 0.55 − (−0.05) = 0.60. (1 mark)
2. The interval includes zero, so the data are compatible with no effect. (1 mark)
3. The upper end, 0.55, is a medium effect, so a useful effect is also compatible. (1 mark)
4. Fair summary: the result is uncertain, and more or larger trials are needed. (1 mark)

Step 6 Learner practice (instant-marked)

Step 7 Recap

• Meta-analysis pools many studies.
• Goyal and colleagues (2014): 47 trials, 3,515 participants; moderate evidence for anxiety (0.38), depression (0.30) and pain (0.33); low evidence for stress and quality of life.
• A confidence interval shows which effects the data are compatible with.
• “Low evidence” is not “does not work”.

Step 8 Exit ticket (ungraded)

Write one sentence that fairly summarises the depression result, including the interval.

Your sentence

Private: nothing you type here is sent or stored.

Step 9 Go further (Extension)

Read the abstract of Goyal and colleagues (2014) in JAMA Internal Medicine. Find what the review says about comparison groups and about whether meditation was better than other active treatments.