I'm not from IA. In an effort to understand caucus dynamics a little bit, I pencilled out the below. Let me know if you see errors or see different gaming possibilities. This clearly gets more interesting with more candidates. Not all supporters are likely to be willing to engage in strategic voting but in these small precincts a small group of strategic voters may be enough. The average precinct only has about 100 voters and these are smaller than average.
Basically, in a two way race the weaker candidate has an advantage in delegates in precincts with an even number of delegates, and the stronger candidate has an advantage in precincts with an odd number. In precincts with 3-6 delegates, in a two way race, strategic voting could sometimes be used by the weaker candidate to deny delegates to the stronger candidate without themselves losing delegates.
For a precinct with only one delegate, caucusing continues until one candidate (or uncommitted) has a majority. In such a precinct, the viability level is 50% rather than the commonly heard 15% (which applies to precincts with 4 or more delegates).
In a precinct with 2 delegates the viability level is 25% and a candidate above that level would get 1 of the two delegates.
In a precinct with 3 delegates, the viability level is 1/6th and a candidate above that level will receive at least one delegate. If only two candidates are viable the one with more support receives two delegates. If that support is less than 2/3rds, strategic voting by the minority can deny that candidate a second delegate and make a 3rd candidate or uncommitted viable. Example (if Hillary has 55% support on the first ballot and Bernie voters have 35% (with 10% split between MOM and uncommitted) if Berniacs split 50-50 on the second ballot they can give the same one delegate to Bernie while giving a second to uncommitted. The Berniacs caucusing as uncommitted can then elect an “uncommitted” closet Berniac to the county convention. If a minority of Hillary voters switch to uncommitted to prevent this and protect county level support it still results in reduced HRC delegate count for the media report after the precinct caucus.
In a precinct with 4 delegates, viability is 15% but a candidate needs 55% to guarantee two delegates (otherwise a 3 way split of the opposition can take 3 of 4) and 62.5% at minimum to receive 3. The minimum level of support to receive two delegates is 37.5%. Between 30-37.5 minority support strategic voting could deny a nominal delegate to the stronger candidate while retaining the single delegate for the weaker of the two.
Assuming no strategic voting and a two way race the support levels needed for 1 delegate are 15%, for 2 delegates 37.5%, for 3 delegates 62.5%, and for 4 delegates 85%+
For a precinct with 5 delegates viability is still 15%. Without strategic voting in a two way race, 15% is one delegate, 30% is two, 50%+ is 3, 70% is 4, 85%+ is 5. At 45-50% support with strategic voting it is possible to keep the same two delegates and deny the stronger candidate a third.
For a precinct with 6 delegates, the viability level is still 15%. With no strategic voting in a two way race: 15% is one delegate, 25% is two, 41-2/3rd is three, 58-1/3rd is four, 75% is 5, and 85%+is 6.
For a precinct with 7 delegates, the viability level is 15%. With no strategic voting: 15% is one, 3/14ths is two, 5/14ths (35.7%) is 3, 50%+ is 4, 9/14ths (64.3%) is five, 11/14ths (78.6%) is 6, and 85%+ is 7. For precincts with 7 delegates or more the viability level is larger than the proportional share of a single delegate.
for precincts with 10 delegates the viability level is 15%, 15% is two delegates, 25% is 3, 35% is 4, 75% is 8 and 85% is 10.