Table 6.

Multiple linear regression estimates including the intercept and the significance levels.

Model		Unstandardized coefficients		Standardized coefficients	T	Sig.
		B	Std. error	Beta
1	Constant	−268.119	146.782	—	−1.827	0.073
	Temperature (°C)	7.267	4.708	0.162	1.543	0.129
	Academic qualification	−12.732	10.348	−0.138	−1.230	0.224
	Years of working experience	−1.597	13.870	−0.014	−0.115	0.909
	Age of facility (beauty salon)	59.091	20.969	0.303	2.818	0.007
	Number of services	20.397	9.465	0.137	2.155	0.036
	Average number of customers in a week	47.445	12.556	0.444	3.779	0.000
2	Constant	−266.598	144.844	—	−1.841	0.071
	Temperature (°C)	7.180	4.606	0.160	1.559	0.125
	Academic qualification	−12.741	10.253	−0.138	−1.243	0.219
	Age of facility (beauty salon)	58.372	19.833	0.299	2.943	0.005
	Number of services	20.537	9.301	0.238	2.308	0.032
	Average number of customers in a week	46.901	11.526	0.439	4.069	0.000
3	Constant	−256.037	145.308	—	−1.762	0.084
	Temperature (°C)	6.851	4.621	0.152	1.483	0.144
	Age of facility (beauty salon),	61.753	19.743	0.316	3.128	0.003
	Number of services	16.624	8.794	0.193	1.890	0.064
	Average number of customers in a week	43.451	11.242	0.406	3.865	0.000
4	Constant	−45.825	32.140	—	−1.426	0.159
	Age of facility (beauty salon)	62.855	19.939	0.322	3.152	0.003
	Number of services	18.443	8.801	0.214	2.096	0.041
	Average number of customers in a week	46.625	11.154	0.436	4.180	0.000

^aDependent variable: formaldehyde concentration (CL (μg/m³)).