TABLE 5.

66 research findings from 13 studies on the effect of happiness trainings on happiness, only studies with control group and follow-up measurement effect sizes expressed in % change on scale range.

Nature of happiness training	Method of investigation
	Longitudinal before versus after training
	Change in treated group only		Difference with change in control group		Follow-up time
	Post-intervention	After follow-up	Post-intervention	After follow-up
Best-possible-self exercise	+5.1	+1.6	+0.5	−2.3	2 months
Goal-setting training	+3.6 +5.1a	+1.1 +1.6a	0 +0.5a	0 −2.3a	2 weeks
∙ Live up to one’s values	+4.0	+2.5	+7.8	+5.8	2 weeks
Meditation, mindfulness	+4.6	+5.6	−0.6	−0.7	6 weeks
Novelty trying	+3.6a	+1.1a	0a	0a
Mood awareness training	+3.9/+3.7/+0.7c	+4.2/+3.7/+1.2c	+2.0/+4.0/+0.7c	+0.4/+1.1/+1.1c	2 weeks
Positive thinking training	+2.4	+7.0	−0.4	−2.9	6 months
∙ Gratitude training	+1.5	−0.7	−0.8	−0.2	2 months
Savoring training	+1.3	+0.3	+1.6/+1.1	−0.2/-0.1c	1 month
Training of multiple mental skills	+19.5 +10.0 +6.7 +3.7 +15.2/+14.8c	+13.9 +30.8 +15.8 +0.4 +11.8/+14.8c	+29.0b +8.3 +3.4 +2.0 +23.8/+23.4b	+27.9b +10.4 +10.4 −10.8 +23.4/+25.4b	6 months/1 year 1 year/3 months 4 weeks
Number of studies and participants
Number of studies	13	13	11	11
Participants (n)	945	933	1,441d	1,416d
Mean n	73	72	131	129
Median n; range	43; 10–306	43; 10–306	79; 37–360	79; 37–360
Results
Mean change	+6.2%	+7.3%	+2.2%	+0.9%
Median change	+4.0%	+3.0%	+1.4%	+0.2%

Percentages change in upper part of the table link to finding page inWorld Database of Happiness. Click linked percentages in upper part of the table to view the page. a: not included in calculation of mean/median because study appears twice in column. b: Not included in calculation of mean/median because of huge decline in happiness in control group. c: Average effect of multiple measures in study used in calculation of mean/median. d: Numbers of participants and controls added up.