We get a lot of questions on how reliable the measurements collected by NetSpot are. The broad answer is that there’s nothing _absolutely reliable_ in this world. Depending on your specific use case, whether it’s a business or home WiFi setup, you’ll have to decide about the acceptability threshold yourself.
In our point of view, any hardware (no matter how expensive and well-calibrated it is) can go offline or start glitching at any point of time. Any receiving or transmitting hardware can fail or lag. Our app visualizes the available data collected by a real device (that you choose to use for WiFi polling, running Windows, macOS or Android).
An alternative is to use a [much] more expensive expert-level hardware created solely for the purpose of measuring WiFi radios. Is that one “absolutely reliable” at all times? No, as it is also prone to failure. Also, a dedicated hardware is usually more sensitive than the real-life end-user devices, and would normally paint a more “optimistic” picture this way. There’s no official standard for this kind of physics or math.