HOW SWB CELLULAR CALLS WERE SELECTED FOR TRANSCRIPTION

(1) A listing was created with one row for each of the 250 subject pins; the 
first column of each row contained the "target" subject pin, and the second 
column contained a list of the pins for each of the participants that had 
spoken to the target in successful calls.  So the second column varied in 
length according to the number of calls completed by the target subject in the 
first column.

(2) The rows of this listing were sorted in order of increasing length, so 
that subjects who completed only one call were listed first and the subject 
involved in the most calls was listed last.

(3) The list was then processed by a simple perl script that applied the 
following algorithm:

  let "done{pin}" be an array that counts how many times a subject is selected
  foreach row
    if the target pin has already been "done" (selected), skip this row
    else
      look at each pin in the second column
      pick the first one that has not yet been "done"
      if all pins in the second column have been "done",
	pick one that has been "done" fewest times so far
      having picked a partner for this target pin, 
	increment "done{target}" and "done{partner}"
	output this pair of pins

(4) The first pass of that perl script yielded a list of 128 calls that 
involved all 250 pins at least once.  In order to select more calls, the 
script was run again with a few modifications:

  first, read the list of selected target/partner pairings created by pass 1
  foreach pairing
    increment "done{target}" and "done{partner}"
    let "found{'target partner'}" be an array to store established pairs

  read the sorted listing of targets and all their participants
  foreach row
    if the target has been "done" MORE THAN ONCE overall, skip this row
    else
      look at each pin in the second column
      try to pick one that has has not already been paired with this target,
                 and has been "done" the fewest times so far
      if a partner was pickable for this target pin, 
	increment "done{target}" and "done{partner}"
	output this pair of pins

(5) The output of the second pass yielded an additional 118 calls, involving 
the 231 pins that had made two or more successful calls.  Appending this to 
the first-pass selections, we had a total of 246 calls.  Four more were 
selected by hand to bring the total to 250.

	Dave G.