Impact Scale
How big is the effect? This scale rates whether you'd actually notice the difference in real life. The "Effect size" column uses Cohen's d (or Hedges' g, which is nearly identical): it measures how far apart two groups end up, in standard-deviation units. Think of it as "how many notches apart are the meditators and the non-meditators on the results dial."
| Score | Label | Effect size (d / g) | What it means | Example |
|---|---|---|---|---|
| 5/5 | Life-changing | above 0.8 | You'd notice this without a study. Like the difference between exercising and not exercising. The two groups barely overlap. | Rare in psychology. Most pharmaceutical drugs don't reach this. |
| 4/5 | You'd feel it | 0.5 to 0.8 | A clear, noticeable difference in daily life. If you ran the experiment on yourself, you'd probably feel something changed. | Mindfulness on anxiety (g = 0.56). Positive emotions boosted beyond 69% of the control group. |
| 3/5 | Meaningful | 0.3 to 0.5 | A real effect that shows up in groups, but you might not spot it in any single person. Comparable to many effective medications. | MBSR on stress (d = 0.32). Most successful positive psychology interventions land here. |
| 2/5 | Subtle but real | 0.15 to 0.3 | Statistically reliable, but hard to detect at the individual level. A nudge, not a shove. Still valuable if you keep doing it. | Meditation on sustained attention vs. another activity (g = 0.19). Many approved medications operate here. |
| 1/5 | Barely there | below 0.15 | Detectable only with large samples and careful statistics. Probably not meaningful for one person. | Not worth citing for Reborn's messaging. |
How to read effect sizes in plain language
An effect size of 0.2 means: if you picked a random meditator and a random non-meditator, the meditator would score higher about 56% of the time (instead of the 50/50 you'd expect by chance). At 0.5, that number rises to about 64%. At 0.8, roughly 71%.
Small effects still matter when they compound over time or apply to millions of people. But for Reborn's messaging, we want to cite studies that land at 3/5 or above: effects a single user could plausibly feel.