We analyzed the predicted RT error distribution for the CE dataset in more details (Figure ). It was found that the distribution was asymmetric, with heavier tails than in the case of normal distribution. Most likely, the heavy tails were due to the presence of either false positive or misallocated data points (estimated as ca. 5.8% of the data according to the manual RE dataset analysis results). The blue histogram in Figure contains 99% of the data within the range of RT = -25…20 s, with the remaining 1% falling into the first and last bins of the histogram. The skewed t-distribution reflected the actual distribution with the highest degree of precision (yellow line in Figure ). The predictions were slightly biased towards the lower values of RT (mean ∆RT was -0.33 s). Such error behavior can be explained by the influence of non-retained compounds, which appear as a small peak at the start of the RT scale (Figure in Supporting Information). Notably, the RT distribution in the METLIN dataset was also bimodal, although the gap between the retained and non-retained compounds was more noticeable. Such data distribution is caused by the nature of the compound's behavior during LC resolution and can be a challenge for a proper model building. Therefore, the information on non-retained compounds is valuable, although it is tempting to simply exclude such compounds to obtain better prediction results.