Table 2.

Multiple linear regression analysis between radon concentration and the factors affecting the increased concentration

Radon concentration	Unstandardized coefficients		P value	95% confidence interval for B
	B	Std. error		Lower bound	Upper bound
(Constant)	31.64	5.29	0.000	20.981	42.299
Duration of smoking	0.098	0.032	0.003	0.034	0.162
Number of cigarettes	0.769	0.254	0.004	0.257	1.281
Use of stone for flooring	0.102	0.037	0.008	0.028	0.176
Pulmonary disease	−5.32	2.641	0.049	−10.645	−.012