Without a more extensive and detailed survey, only speculation as to the discrepancy can be made.
Christianity Today
During my time at the school, 50 students were chosen to participate in a detailed survey of their development.
Times, Sunday Times
By making a detailed survey of the surfaces with instruments far superior to those on previous probes, it will detect any tell-tale signs of a biosphere beneath the surface.
Times, Sunday Times
A detailed survey of 46 very different species found that some had almost constant levels of fertility throughout life while others appeared to become stronger the older they got.
Times, Sunday Times
Officials say, however, that they have not carried out a detailed survey of lenders to ascertain whether the funds will be available.
Times, Sunday Times