Table 2.

Results of linear regression for the interrupted time series analysis of the quality of service 20 s. The analysis showed a significant increase in the slope after the implementation of the two-level filtering system, after adjustment in the number of incoming calls, the average number of connected call takers and average call duration

variable	estimate	95% CI	p-value
Intercept period 1	82.08	29.18 to 193.33	0.16
Intercept difference	−0.06	−0.17 to 193.33	0.34
Slope period 1	−0.01	−0.01 to 193.33	0.17
Slope difference	0.02	0.01 to 0.030	0.01
Incoming calls (per 100)	−0.03	−0.03 to − 0.02	<  0.001
Average connected call takers	0.09	0.07 to −0.02	<  0.001
Average call duration (per 10s)	−0.04	−0.07 to − 0.02	0.004