Exponent made detailed measurements of a football's bladder when both wet and dry. The difference is so small, it is within the uncertainty of the measurement devices.
A bigger difference would be the change in atmospheric pressure during the game. During the first half of the 2015 AFC Championship game, the atmospheric pressure declined by 0.07 psi. All else equal, this would increase the measured pressure of the ball by 0.07 psi. (Think of taking a bag of potato chips to a high altitude. The decrease in air pressure makes the bag puff out.)
During the December 4 game in Pittsburgh, the atmospheric pressure declined by 0.03 psi. The change in atmospheric pressure is more statistically significant than the impact of a wet football.
There can be up to a 3% change which can be significant with a wet versus a dry football. It makes logical sense because as the leather absorbs water it expands and becomes softer, which allows the volume to increase, which is going to decrease the pressure more.
The Exponent analysis is flawed, and was commissioned with an end result to be achieved. It is in no way independent, apart from the flawed conclusions.
Exponent?!?!?
Ooooo...WOW!
Exponent? Ted Wells? A match made in heaven, given that the one is an apparent agent of the Dark Lord, and the other authors hit pieces that would make most any 9th grader blush.
But I know - we have a subject here that doesn’t have much depth, so...
Maybe it’s time we all moved up to the next thread of interest!
CA....
Exponent made detailed measurements of a football’s bladder when both wet and dry. The difference is so small, it is within the uncertainty of the measurements.
You might notice that the result actually varies according to which page. 0, .1, .2, .3, and .5 PSI are all differences you can find in their graphs. Even their fudged graphs (which you might note don’t remotely match their experimental results).
You might also note that their ‘0’ laser measurement has a resolution incapable of reliably discriminating between volume differences which could be as great as just over 1 PSI. ...but boy was it fancy!
You might also note that their method of wetting the ball was grossly inadequate to duplicate the conditions. If I recall correctly, also done only with one ball.
You might also note that volume change plus evaporative cooling has been repeatedly shown experimentally to top out at about a 0.95 PSI drop at the pressure and temperature ranges. Use a wet-bulb calculator to get the gist. According to the Wells report, the indoor humidity was about 20%. You can use that figure in your calculations.