Does the quality management system affect working capital management efficiency? Evidence from Polish firms

Figures & data

Table 1. Descriptive statistics

Variable	Obs	Mean	Std. Dev.	Min	Max
WCME	84	65.7	35.5	−11	150
ISO	84	0.33	0.47	0.00	1.00
ROS	84	0.06	0.09	0.00	0.80
SIZE	84	0.45	0.50	0.00	1.00
LEV	84	0.43	0.21	0.05	0.84

Note: This table reports the descriptive statistics of the study variables. These variables include working capital management (WCME), quality management system (ISO), return on sales (ROS), firm size (SIZE), and leverage (LEV).

Table 2. Pairwise correlations and multicollinearity results

Variable	CCC	ISO	ROS	SIZE	LEV
Panel A: Pairwise correlations.
WCME	1.000
ISO	0.147	1.000
ROS	0.245*	0.250*	1.000
SIZE	0.086	0.727*	0.248*	1.000
LEV	−0.541*	0.027	−0.205	0.155	1.000
Panel B: Variance inflation factor and tolerance.
Test		ISO	ROS	SIZE	LEV
VIF		2.17	1.15	2.26	1.11
1/VIF		0.46	0.87	0.44	0.90

Note: This table reports the results of the pairwise correlations and multicollinearity tests of the study variables. These variables include working capital management (WCME), quality management system (ISO), return on sales (ROS), firm size (SIZE), and leverage (LEV). * Significant at 0.05 level.

Table 3. Differences analysis

Variables	Means		Levene’s Test for Equality of Variances		Z-test for Equality of Means
	ISO adoption	ISO neglection	F	Sig.	Z	Sig.
WCME	73	62.02	0.512	0.476	1.345	0.182

Note: This table reports the results of the independent sample test to verify the significant differences between the means of the study groups in terms of ISO standard adoption.

Table 4. Regression analysis per period

Independent variables	Coef.	Std. err.	t	P>|t|	[95% conf. interval]
Panel A: The first period of the COVID-19 pandemic
ISO	2.898	13.51	0.21	0.831	−24.48	30.28
ROS	24.61	42.54	0.58	0.566	−61.58	110.8
SIZE	11.32	12.99	0.87	0.389	−14.99	37.65
LEV	−101.9	23.50	−4.34*	<0.01	−149.53	−54.32
_cons	105.5	12.14	8.69*	<0.01	80.91	130.11
Num. of obs = 42			R-squared = 0.393
F(4, 37) = 5.98			Adj R-squared = 0.327
Prob > F = <0.01
Panel B: The second period of the COVID-19 pandemic
ISO	9.457	16.11	0.59	0.561	−23.19	42.12
ROS	180.2	173.3	1.04	0.305	−170.9	531.2
SIZE	−2.547	16.53	−0.15	0.878	−36.04	30.94
LEV	−81.54	25.18	−3.24*	<0.01	−132.6	−30.53
_cons	85.96	14.85	5.79*	<0.01	55.88	116.04
Num. of obs = 42			R-squared = 0.303
F(4, 37) = 4.03			Adj R-squared = 0.228
Prob > F = <0.01

Note: This table reports the results of regression estimations using ordinary least squares (OLS) regression. * Significant at the 0.05 level. The variables include quality management system (ISO), return on sales (ROS), firm size (SIZE) and leverage (LEV).

Table 5. Regression analysis over the study period

GLS regression
Number of obs = 84			Wald chi^2(4) = 16.18
R-squared: Overall = 0.3232			Prob > chi^2 = 0.0028
Independent variables	Coef.	Std. err.	Z	P>|Z|	[95% conf. interval]
ISO	4.334	11.64	0.37	0.710	−18.49	27.16
ROS	6.093	18.80	0.32	0.746	−30.76	42.94
SIZE	9.349	7.975	1.17	0.241	−6.281	24.98
LEV	−68.83	18.82	−3.66*	<0.01	−105.7	−31.93
_cons	89.22	9.991	8.93*	<0.01	69.63	108.8

Note: This table reports the results of regression estimations using generalised least squares (GLS) regression. * Significant at the 0.05 level. The variables include quality management system (ISO), return on sales (ROS), firm size (SIZE) and leverage (LEV).

Table 6. Robustness tests

Independent variables	Analysis using the OLS technique	Analysis using the bootstrap technique	Analysis using AR(1) disturbances	Analysis using an alternative measure for CCC	Analysis using an alternative measure for ROS
ISO	4.969 (10.12)	4.334 (9.447)	4.611 (11.16)	0.190 (0.758)	6.281 (10.54)
ROS	37.99 (39.94)	6.093 (113.01)	7.202 (20.08)	0.552 (1.273)	-
ROA	-	-	-	-	12.37 (60.95)
SIZE	6.965 (9.781)	9.349 (6.305)	9.002 (8.195)	0.259 (0.533)	7.583 (10.44)
LEV	−92.09* (16.53)	−68.83* (27.94)	−74.11* (18.34)	−5.928* (1.234)	−94.45* (17.70)
_cons	98.32* (8.354)	89.22* (17.05)	91.49* (9.588)	5.519* (0.651)	99.70* (10.72)
Num. of obs	84	84	84	84	84
F (Prob > F)	9.85 (<0.01)	-	-	-	9.53 (<0.01)
Wald chi^2 (Prob > chi^2)	-	12.19 (<0.01)	19.16 (<0.01)	24.39 (<0.01)	-
R-squared	0.3329	0.3232	0.3257	0.2770	0.3256
Adj R-squared	0.2991	-	-	-	0.2914

Note: This table reports an additional analysis for the robustness test; * indicate that coefficients are statistically significant at 0.05 level; Standard errors in the model are reported in parentheses; The variables include quality management system (ISO), return on sales (ROS), return on assets (ROA), firm size (SIZE) and leverage (LEV).