## 5 Conclusions and Future Work  
The analyses presented in this article provided detailed information about the concentration of OSM geodata and its contributors for 12 selected worldwide urban areas. The main objective of the article was to determine similarities or significant differences between the selected areas regarding their data growth and collection efforts by the OSM community. The results showed that the urban areas provide significantly different data concentrations in OSM, which can be caused by data imports for selected areas or large differences between community contributions. The results also highlighted the differences between European and other world regions in OSM. Especially the number of OSM members can differ largely in this case. With the exception of Istanbul, all tested European areas show higher OSM member concentrations than other areas with high population density values such as Cairo or Seoul. Moscow proved to be a positive example outside of Europe with a large OSM community. When splitting the OSM contributors into different groups, based on their number of edits made to the map data, all tested areas show similar patterns. About 7% of the data contributors are very active \"Senior Mappers\" while 28% fall into the Junior Mapper category with fewer contributions. The largest group of data collectors is represented by the \"Nonrecurring Mappers\" with 66%. The determination of the active time frames of the members showed that about 16% of all OSM contributors in each area have been active within three months by making at least one edit to the map. However, only 3% of the members can be considered as very active \"Senior Mappers\". The data also revealed that the absolute number of active OSM members has no impact on the activity spectrum of the volunteers. The most active \"Senior Mappers\" created on average about 90% of the data in the urban areas and worked on about 9 of the tested 90 days and created almost 1500 Nodes, 230 Ways and 4 Relations total. The temporal data quality proved to be highly influenced by the size of the community in each urban area, which confirms similar findings for France [13]. Smaller communities do not guarantee continuing data collection or correction efforts and thus make the datasets outdated. Further results were gathered by analyzing and comparing local to external data contributors. Especially urban areas with lower OSM community member numbers show large (sometimes more than 50%) external member data contributions. Especially Cairo, Istanbul, Johannesburg and Los Angeles rely on these non-local members. In general, this pattern contradicts in certain aspects the main idea behind VGI projects as defined by [PERSON] [42] in which \"local volunteers\" should be the main source of information. However, Neis & Zipf [16] already proved that more than 50% of the worldwide \"Senior Mappers\" of the OSM project contribute data to two or more countries and do not limit their efforts to local areas. Due to the fact that the population density did not provide enough evidence of impacting OSM member numbers, other socio-economic factors were taken into consideration. It was hypothesized that income might be a major influential factor. The analysis showed that urban areas with higher income values such as Sydney, Los Angeles, Seoul and Osaka could potentially inherit larger OSM communities than currently available but still show a correlation between income and OSM contributor ratio. Berlin has a slightly lower average income in comparison to other tested areas and a relatively high member density, but can be considered as an exceptional case. Overall the conducted analyses do not completely confirm prior results gathered for England where \"more affluent areas and urban locations are better covered than deprived or rural locations\" [9]. However, a more comprehensive investigation with additional urban areas, which increases the sample size, could improve the findings of our analysis and statistical results presented.