NOECs and LOECs are determined by hypothesis testing (Dunnett's Test, a t test with the Bonferroni adjustment, Steel's Many-One Rank Test, or the Wilcoxon Rank Sum Test with Bonferroni adjustment), whereas LCs, ICs, and ECs are determined by point estimation techniques (Probit Analysis, the Spearman-Karber Method, the Trimmed Spearman-Karber Method, the Graphical Method or Linear Interpolation Method).
Hypothesis testing is how LOECs are found.