The density--i.e., the ratio between the number of edges and the number of nodes--has increased over time with a coefficient larger than 1 and less than 2 for all five conference series (Figure 4a), whereby the coefficient is largest for ITS (1.38) and ECTEL (1.24), and smallest for ICWL (1.05).
92) although it has dropped over the years, but Figure 4d shows that AIED and ECTEL have quickly growing largest connected components (i.e., the core author group described for the development model above) indicating a faster scientific community building process than for ICALT and ICWL. ITS has the largest core author group of all five conferences, but it needed longer to develop, since the size remained at an almost constant low value for the first three ITS events.
ICALT and ICWL do not exhibit such a clear pattern, while AIED and ECTEL are developing very fast in this regard.
ICWL, on the other hand, is as old as ICALT, and still seems to struggle with managing the transition from the emergence stage to more mature stages in the development pattern shown in Figure 1.
The clustering coefficients of all conferences are similar, with ICWL exhibiting a higher coefficient than the other four conferences (Figure 5b).
The other two conferences, ICALT and ICWL, have developed more slowly, but they still follow the same pattern.
Given the comparison of network structures of TEL and database conference communities, and in particular the case of ICWL, we attempt to understand the strategy by which conferences develop their community.
For TEL conferences, the fraction of recurring authors and their publications in ICWL ceased to increase during the last five years.
In more interdisciplinary conferences like ICWL, authors return to the conference at a lower rate.
In this paper we have explored the structural development of the Technology Enhanced Learning (TEL) scientific community by analyzing the development pattern of co-authorship networks of five major international conference series in TEL which have particular relevance for authors who have also published papers in the ET&S journal: ICALT, ICWL, ECTEL, ITS and AIED.
On the other hand, it slows down the process of building a core group of authors, as we saw, for example, in the relatively slow development pattern of ICWL compared to faster developing, more focused conferences like AIED and ITS, which have a clear artificial intelligence focus, or ECTEL, which has its geographic and thematic focus in European TEL.