Hi Bob,
By random, I mean how close to algorithmically random the statistical sample is. Algortihmically random being random with the lucky rolls removed, what you approach if you roll the dice a lot.
In this case, we could use sophisticated techniques like fuzzy k clustering or whatever to test the randomness of Thomas, but I'm not so sure the results would be as strong. Lots of arbitrary choices, and far from intuitively clear you've accomplished anything.
But, given the number of possibilities, (number of sayings or partial sayings in Thomas), and number of instances, (number of Mark sayings or partial sayings), you can calculate the probability the largest gap (those 32 between 66 and 69) would happen if you rolled dice.
In other words, what is the probability that 32 saying gap would happen by random chance, and it's less than 1 in 100.

As for it being Poppycock, I'll turn the other cheek, even though I don't think Jesus ever said it, and it comes to us from Paul, through the Didache.
I looked pretty hard, because I had a hard time getting a handle on it, and it sure seemed to be something someone would have done before. I did find a site with a "Mister Statistics" where people would ask obscure statistics questions and he would answer them. He came up with a solution, but it was wrong, which one of the posters pointed out, to his embarrassment, so he said he'd get back with the answer, but never did. So, it's relatively obscure, at least.
But it's there, and it's hard pure math, and anyone comfortable with math can point out any error, certainly after my clarifying it, and determine if it's poppycock. Who knows, perhaps their literature search and/or knowledge of statistics will find a case of someone else doing it before. Hard for me to say about that, but I'm pretty certain the math is correct. For what it's worth, it wouldn't be the first time I solved a logic puzzle others seemed to find difficult.

Flipping a coin doesn't work logically, Bob, because the probability of a saying being a Mark saying in Thomas isn't 50/50. And, as Mark sayings are used up in your dice rolling, the odds change, depending on the luck of the dice in the first part. It's a more difficult puzzle than it first appears.
The bottom line, Bob, is that less than 1 out of 100 cases, with that many Mark sayings out of 114, if random, will have a gap of 32 or more. Mathematical fact. Easy money at Las Vegas if they will bet against it.
And no, from what I've seen, Biblical scholarship is rather weak on the math. Still waiting for one person to even be able to follow the relatively simple math/logic I presented. Granted I probably did a poor job of explaining it, but I'm here to answer questions. It's a universal system for testing randomness, not just Mark in Thomas.
I hope that addressed all your points, if I missed one, let me know.
Rick Van Vliet