Originally Posted by
CDF
It seems 1.55 is more likely a consequence of flooring than testing methodology, so let's just leave it at that. Now, for more speculation.
Another observation about 1-handed pDIF behavior: it seems that along with a maximum critical pDIF cap of 3.0, there could be a minimum non-critical pDIF floor of 1.0 for certain ranges of attack/defense ratio. So, pDIF of 1.0 shows up more than you would expect. Then, when the secondary randomizer is applied, that could be why you get the observed spike at left endpoint of the observed empirical distribution.
Now, for lower ranges of attack/defense ratio, the base pDIF distribution could still be uniform. Then, a function could be applied that turns 50% of the randomly selected pDIF values to 1.0 pDIF, which could be why pDIF 1.0 shows up more than expected. Then, when you apply the secondary randomizer, that could be why there is the observed spike sitting in the middle of the observed empirical distribution. Perhaps, as the attack/defense ratio goes lower, the "spike" would shift to the right.
Finally, I doubt anything in this game is really continuous. As we have already seen for hit rate and critical hit rate, 0.5% increments are not possible, so we probably should consider pDIF and the "secondary randomizer" as being discrete probability distributions in a sense, and I said in the past, the sum of two uniform random variables follows a trapezoidal distribution, which can describe the observed shape of pDIF.