How movable is movable nu?

A question arose from someone about while reading LGPSI, about the distribution between ἐστί and ἐστί(ν), specifically they noted that I sometimes (perhaps more frequently than expected), violated the general rule that movable nu appears before a subsequent vowel. Now, I happen to know intuitively that that rule is by no means hard and fast, but since the question was raised, I was intrigued enough to ask, how much is that rule breached rather than followed. I was also motivated by the desire to make sure that LGPSI doesn’t merely reflect grammars, but reflects usage patterns.

So, as with all such useful questions, I knew who could not only probably tell me, but also help me understand the process of how to answer such questions, James Tauber. He helpfully shared with me snippets of his own code that could be brought to bear, and then ran the data himself on the SBLGNT.

Now, the SBLGNT is a modern edited text, so the results it provides probably say something more about the editor, than they necessarily do about ancient texts. That suggests to me that there’s good room to ask the same kinds of questions at a manuscript level, and also at broader corpus levels.

Looking at strings of characters and where movable nu, and movable sigma (e.g. οὕτως vs οὕτω) occur, yields some of the following data.
Of 162 instances of words that could end with either movable nu or sigma but do not (e.g. they are movables that end with a vowel), they are followed by a word starting with a vowel only twice only twice, and those are Luke 16.16: μέχρι Ἰωάννου, and Acts 1.15 εἴκοσι)· Ἄνδρες.

Of 5081 numbers of movable nus that do occur, 1480 occur before a vowel, 749 before a vowel with rough breathing, with no intervening punctuation. The presence of a subsequent vowel appears to be no barrier to the presence of a movable nu. Whereas the absence of a movable nu and/or sigma does appear to require a consonant-initial to follow. (Numbers exist too for when punctuation intervenes, which doesn’t contradict the overall pattern).

Similarly, perhaps, a movable sigma occurs 188 instances in which there is no following punctuation, 107 times of which have a following consonant – suggesting that like movable nu, a subsequent consonant does not deter a movable sigma.

But, all that said, ἐστι (whether ἐστί or ἔστι), occurs but 6 times in the SBLGNT, which may suggest something. Does it suggest more about Holmes’ editing of the SBLGNT, or about movable nu usage in the New Testament corpus? The only way to answer that would be more data analysis.

For now, and for my own purposes, I’ll be less worried about ἐστίν before consonants, and perhaps a little more conscious to use ἐστί only before consonants…