[jyl]

How accurately are you trying to measure a given characteristic?

What I mean is, and this probably isn't the right terminology for aerospace, but suppose you are trying to measure fuel consumption at a given airspeed, altitude, etc. Say your tests return sonething around 6.5 gph, making up a number. Do you test enough to determine that it is 6.3 to 6.8 gph to a 95% confidence?

Same question for other performance metrics, rate of climb or roll or whatever.