Estimation accuracy quantified by σ(M_*)/σ_min(M_*) as a function of k for the five models defined in Table 2. σ(M_*) refers to the standard deviation of log stellar mass residuals estimated using a given k of nearest neighbors, and σ_min(M_*) refers to the minimum value over the k grid for each model. The error bars are obtained using bootstrap. The points at k = 1000 and k = 2000 for the model I_u𝑔riz ∪ M_W123 ∪ ɀ_spec are not shown due to significantly high values.