Table 2.

The results of the subgroup analysis on the differences of the subjects’ continent of origin, type of data, probing, sample size, laterality, and study quality on the estimated prevalence

Predictor	Moderator (subgroup)		k	Prevalence (95% CI)	QM	QE
Continent of origin	Europe		5	36.2% (26.7–45.8)	0.845	< 0.0001
	America		8	36.4% (28.4–44.4)
	Asia		13	39.9% (29.7–50.1)
Type of data	Imaging		3	48.8% (20.1–77.5)	0.401	< 0.0001
	Dried skulls		23	36.4% (31.7–41.0)
Probing	No		11	35.8% (30.4–41.1)	0.508	< 0.0001
	Yes		15	39.2% (30.7–47.6)
Instrument used	Wire		7	40.2% (23.3–57.0)	0.941	< 0.0001
	Bristle		3	32.5% (26.7–38.3)
	Other		5	43.5% (39.3–47.7)
Dominance	Unilateral		16	33.1% (28.1–38.1)	0.016	< 0.0001
	Bilateral		10	46.0% (36.8–55.3)
Sample size	Small		17	37.5% (31.9–43.2)	0.842	< 0.0001
	Large		9	38.6% (29.3–48.0)
Study quality	Moderate		17	35.7% (31.4–40.1)	0.473	< 0.0001
	High		9	40.4% (28.4–52.5)
Measurements	No		12	41.5% (36.9–46.2)	0.198	< 0.0001
	Yes		14	34.8% (25.6–44.0)
Instrument used	Caliper		6	34.0% (24.6—43.5)	0.084	< 0.0001
	DICOM Viewer		3	46.0% (13.3—78.8)
	Image analysis software		5	28.3% (18.2—38.3)

In bold text, the statistically significant findings are being noted

k number of studies combined, Q_M p value of the test of moderators, Q_E p value of the test of residual heterogeneity