## 6 Discussion  
In this part of the paper we discuss the findings in relation to the literature, the limitations of the study, as well as implications for both future research and practice. First, as opposed to our first two hypotheses, the ability (knowledge and skills) to procure in a sustainable manner did not have a positive effect on all types of SPP. The perceived degrees of skills related to SPP did not have a significant effect (positive or negative) on any of the SPP types. Having the skills to professionally procure in a sustainable manner might thus be important, but it will not increase the perceived degree of any type of SPP. A high perceived degree of knowledge also did not have a direct effect on any of the SPP types. It did, however, have an indirect effect on GPP, via affective commitment to SPP. Affective commitment to SPP (or motivation) fully mediated the relationship between knowledge and GPP. This means that the more a procurer feels that they have enough knowledge about sustainability, the more they are affectively committed to implementing it, which results in more implementation of GPP. This contrasts with an earlier finding of [PERSON] [9], who found that both knowledge about SPP and affective commitment had an indirect impact on GPP (via sustainable procurement behaviour), but that they were unrelated to each other. The relationship between knowledge, affective commitment to change and GPP thus requires further research. The finding that knowledge is only (albeit indirectly) related to GPP and none of the other types of SPP does show that implementing these types of SPP might require other abilities than knowledge. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **CMIN/df** & **RMSEA** & **CFI** & **TLI** & **GFI** \\ \hline _Final model_ & 1.143 & 0.022 & 0.992 & 0.974 & 0.987 \\ _Fit criteria good fit_ & \(\leq\)2.00 & \(<\)0.08 & \(>\)0.9 & \(>\)0.9 & \(>\)0.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Goodness of fit tests for the model. Figure 2: The results of the SEM analysis. These abilities, that do play a role in the implementation of the other types of SPP, thus also require further research. Second, as opposed to our third hypothesis, motivation (affective commitment to SPP) also did not have a significant positive effect on the various types of SPP. As mentioned earlier, it only had a significant effect on GPP, but not on any of the other types of SPP. The finding that affective commitment to SPP has a positive influence on the degree of GPP corroborates the finding of [PERSON] [9], but also shows that the antecedents of GPP are not the same as the antecedents of the other types of SPP. Being affectively committed to SPP, and thus being personally convinced of the necessity of SPP, does have a positive effect on the implementation of GPP but not on the other types of SPP. Organisations looking to increase the implementation of various types of SPP cannot therefore simply administer a \"one-size-fits-all\" approach, given that what might drive the implementation of GPP does nothing for the SROI of CIE. This finding thus clearly highlights the necessity to research the implementation of the various types of SPP and to not only focus on the implementation of GPP. This also shows that it is crucial for scholars to provide clear operationalisations of their concepts, and that in future studies, SPP and GPP should not be used interchangeably. They are distinct concepts, which requires them to be studied as such. Third, our fourth hypothesis was that the more opportunities there are for public procurers to procure in a sustainable manner, the more they will do this. We therefore measured the degree of organisation learning capacity that the respondents perceived in their organisation, encompassing for example the degree that organisation supports the development of new ideas, information sharing or involves employees in big decisions.