However, many of these sampled compositions simply fail to form compounds, which underrepresents regions where water modifies crystal formation. Historical reaction data for 4methoxyphenylammonium iodide found that formic acid (FAH) concentrations below 7 M and above 10 M almost exclusively yielded non-crystalline powder or clear liquid, respectively, motivating us to constrain sample to within those bounds, denoted as strategy (b). Those experiments resulted in meaningful difference in the discordant outcomes for 4methoxyphenylammonium (p=0.066), but not for dimethylammonium (p=0.80). (The p-value indicates the probability of the observation under the null hypothesis that outcomes with and without water are the same; lower p-values indicate a better rejection of this null hypothesis.) As formic acid-constrained sampling may not include conditions relevant to each cation, strategy (c) used historical data collected for each cation to construct a convex hull in compositional space where crystal formation occurred and then generated new experiments by a grid sampling of 48 compositions within this region (see Figure ). Experiments using strategy (c) revealed differences in crystal formation with and without water for these two systems, with p=0.00026 and p=0.11 for dimethylammonium and 4-methoxyammonium, respectively. Satisfied that at least one of these sampling conditions would highlight the effect of water on crystallization, all three strategies were used for the remaining two systems, acetamidinium and isopropylammonium. In both cases, strategy (b) resulted in the greatest discrepancy between reaction outcomes with added water, (p=0.013 for acetamidinium, and p=0.029 for isopropylammonium).