Table 2:

The pooled prevalence of water-pipe smoking in college students of Iran

Subgroup		No. of Included studies	Pooled Prevalence (Random Effect)	95% CI	I2	P value for I2
At least once in the Life time		33	25	22–29	98.95	P<0.001
	Male	12	17	15–19	85.19	P<0.001
	Female	14	37	30–45	99.05	P<0.001
At least once in the Last year		8	21	16–25	98.84	P<0.001
	Male	5	31	20–42	98.60	P<0.001
	Female	5	14	8–20	98.19	P<0.001
At least once in the Last month		12	8	5–11	99.70	P<0.001
	Male	7	11	5–16	98.54	P<0.001
	Female	7	4	2–6	96.90	P<0.001
At least once in the Lifetime by sampling method	Census	2	31	29–33	15.25	P=0.91
	Random Cluster Sampling	5	23	17–30	99.2	P<0.001
	Random Sampling	12	20	14–27	98.8	P<0.001
	Stratified random sampling	8	27	22–33	96.6	P<0.001