Table 7.

Excluded variables.

Model		Beta	t	Sig.	Partial correlation	Collinearity statistics
						Tolerance
2	Years of working experience	−0.014a	−0.115	0.909	−0.016	0.707
3	Years of working experience	−0.015b	−0.124	0.902	−0.017	0.707
	Academic qualification	−0.138b	−1.243	0.219	−0.167	0.790
4	Years of working experience	0.013c	0.112	0.912	0.015	0.726
	Academic qualification	−0.128c	−1.140	0.259	−0.152	0.792
	Temperature (°C)	0.152c	1.483	0.144	0.196	0.927

^aPredictors in the model: constant, average number of customers in a week, age of facility (beauty salon), number of services, temperature (°C), and academic qualification. ^bPredictors in the model: constant, average number of customers in a week, age of facility (beauty salon), number of services, and temperature (°C). ^cPredictors in the model: constant, average number of customers in a week, age of facility (beauty salon), and number of services. ^dDependent variable: formaldehyde concentration (CL (μg/m³)).