## 4 Results
The most important conclusions can be summarized in the following points:  
* when controlling the length of financial cycles, no statistically significant difference has been found in the level of profitability of companies with GPO and independent companies (\(p\) = 0.1918)--This means that if you compare companies with GPO and independent companies with a similar length of financial cycles, they also have a similar profitability;
* extending the inventory cycle by one day results, on average, in reducing profitability by 0.033 (ppt)--This impact is statistically significant (\(p\) = 0.0338 *) and occurs regardless of the company's affiliation to GPOs (insignificant interaction group \(\times\) inventory turnover ratio);
* the length of receivables cycles is statistically significant only in interaction with the company's affiliation to GPO (\(p\) = 0.0291 *)--Among companies with GPO, along with an increase in the length of receivables cycles by one day, ROS increases (on average by 0.038 ppt, and among independent companies, the increase receivables cycle causes a decrease in ROS (on average by 0.052 ppt);
* it is similar for the length of the liability cycle (\(p\) = 0.0076 **), but here in the group of companies with GPO, one can observe a decrease in ROS along with the extension of the liability cycle (by 0.042 ppt per one day of the cycle extension of liabilities), and among stand-alone companies an increase in ROS (on average by 0.024 ppt). Companies within GPOs, thanks to the scale of purchases, obtain favourable trade credit. This allows them to gain new contractors through the offer of an attractive trade loan. This policy increases the turnover of receivables from customers within days, however, it translates into an increase in sales and sales profitability. As confirmed by the results in Table 2. The GPO commitment management policy consists of three stages at which the companies operating in GPO receive additional benefits. The most important element of this policy is the possibility of obtaining an additional discount for an early payment. The scale effect allows the purchasing group's central unit to negotiate with producers. The result of these negotiations is an attractive price and a trade credit. The length of the trade credit is the first important information received by companies operating in GPOs. The extended maturity of the trade credit has a large impact on the profitability of enterprises, as they obtain the cheapest source of financing their activities, which are liabilities to suppliers. Importantly, it is the so-called non-interest source of financing because very often in the case of late payment the recipient does not charge penalty interest, especially to regular partners. Thus, the enterprise, thanks to the long-term trade loan, does not have to finance its operations with an expensive bank loan. The long-term payment of liabilities to suppliers makes the receivables management policy with regard to trade credits more attractive, which should attract new contractors who will increase the sales level and margin. The second benefit resulting from an efficient policy of managing liabilities in purchasing groups is an additional discount for an early payment. In the case of GPO, if there is an additional discount, it is basically always used. If such a possibility arises, the central unit makes advance payment, which translates into a low price of the goods purchased. The use of discounts has a very large impact on the increase in the profitability level. However, it results in shortening the deadlines for paying liabilities and a decrease in their share in financing the entity. The fast rotation of liabilities in days for the environment is a clear signal that this company has no financial problems. It is a sign for the environment that it is worth cooperating and trading with such an enterprise. The decrease in the level of liabilities negatively affects the real financial liquidity, as short-term liabilities decrease in liabilities and cash in hand in current assets.