Where is the best place in the basement to set the test?
All other things being equal, we would place the test in a finished area where people are most likely to be spending time and inhaling. Be suspicious of a tester who places the detector close to the sump, which is (a) likely to be a major radon entry point, and (b) not likely to be where people would spend much time. Be especially suspicious if the tester is also someone who does radon fixing.
