5. Discussion and conclusions
This study represents, to our knowledge, one of the first attempts to jointly and separately examine the specific shape of the ID–P relationship in a panel of small, medium and large firms which is representative of a developed country’s industrial fabric. It highlights several important findings. First, strong support is obtained for the three-stage theory, or the horizontal-S curve, in two specific situations: (1) when the full panel of firms (i.e., small, medium and large firms) is considered in the empirical analysis; and (2) when the sample of large firms is considered. Second, sound support is obtained for the argument that the nature and shape of the relationship may vary with firm size, since large firms seem to record a significantly different behavior from SMEs. More importantly, this study also reveals that the nature and shape of the ID–P relationship is quite different for small and medium-sized firms. From this standpoint, it can be concluded that this study provides more fine-grained information than previous research on the true nature of the ID–P link, as the prior focus was on small samples of large firms, samples of SMEs only and, to a lesser extent, large samples with large firms and SMEs, although, in these two latter cases, without distinguishing between small and mediumsized firms. Ultimately, this study provides a more complete and realistic picture of how firms of different sizes may evolve from low to high levels of ID.
