A third factor influencing the project results was the duration of
the participatory sensing campaigns. While potholes VGI was collected
(with scarce results, see above) during almost three months,
architectural barriers were reported in a week and the mapping
parties, by nature, lasted for one day. It is thus clear that, with all
the assumptions made, longer campaigns do not necessarily lead
to the collection of more data. On the contrary, for VGI projects targeting
local people in small areas, short data collection campaigns
have to be preferred because they allow to directly involve the
public and, in turn, get more data.