Can LAAFU effects be modeled?

[ReneZ]

These are roughly as follows:
for first lines, 85% of cases start with one of 'p t k f' (in descending order of frequency).
For all other lines, 85% of cases start with one of 'd s y o q' (in descending order of frequency). Note that the 's' combines the stand-alone s and the left half of Sh, which is not optimal. (I computed these stats using the RF1b file, and both numbers were in fact 84% when rounded to zero decimal places).

There is a bit more to this. The frequency distribution of the first group goes down rather steeply, while the frequency distribution of the second group is almost flat.
Since You are not allowed to view links. Register or Login to view. was brought up just above, the first five characters in the sequnce in the margin are almost the same as these five characters, the only difference being that the y is replaced by a second s. 

This has had me scratching my head for the last four days.
Of course, there is a problem: the fact that s also includes the cases of Eva-sh, and the sequence on You are not allowed to view links. Register or Login to view. also has that one a bit further down...