Does any one know if this test take in consideration wifi strength, whether b,g, or n. Mobile service strength at the time of testing? I believe all of these factors should come into play when testing a browser. Two devices on the same wifi, run test five times clearing cashe between each tast. Depending on the traffic on the wifi at the time of each test will result in different numbers. The way the device interreacts with wifi makes a difference.
If it is just testing your browser than all Five test results should be relatively close whether on wireless or on mobile. If not, there are other factors that need to be considered when looking at the results of the tests.
The "Compatibility" tests should be the same every time (HTML5test and acid3), while the "performance" test can differ (probably will) every single time. Just like performance tests for a PC.
I really dont think the Wifi signal plays any part in them.