Table 3. The mean (SD) age of the First Attempt at Tobacco use in Iranian Adolescents at National and Sub-National Levels: The Caspian-IV Study^a.

	Southeast	North-Northeast	West	Central	National	P Value for Trend
Boys	11.69 ± 3.80	11.90 ± 3.45	12.78 ± 3.30	12.15 ± 3.34	12.31 ± 3.37	> 0.05
Girls	13.42 ± 3.50	13.03 ± 3.16	11.85 ± 3.84	12.79 ± 3.16	12.56 ± 3.41	> 0.05
Urban	12.64 ± 2.23	12.48 ± 3.29	12.65 ± 3.30	12.36 ± 3.26	12.48 ± 3.25	> 0.05
Rural	11.43 ± 4.89	12.01 ± 4.01	11.56 ± 4.38	12.38 ± 3.52	11.90 ± 4.08	> 0.05
Total	12.06 ± 3.75	12.43 ± 3.35	12.48 ± 3.50	12.36 ± 3.29	12.40 ± 3.39	> 0.05

^aValues are expressed as mean ± SD.