q2

{
  "id": "MLC-T-CHM-009712",
  "term": "q2",
  "field": "Chemistry",
  "definition": "A cross-validation statistic for a QSAR model, calculated as one minus the ratio of the predictive residual sum of squares to the total sum of squares of the observed activities, with each compound predicted by a model refitted without it. It is an internal measure of robustness and does not by itself show how well the model predicts an external test set, which needs a separate held-out statistic. A q2 above about 0.5 is conventionally regarded as acceptable.",
  "subject": "Chemistry and Human Health",
  "see_also": [
    "r2"
  ],
  "references": [
    "PAC, 2016, 88, 239. 'Glossary of terms used in computational drug design, part II (IUPAC Recommendations 2015)' on page 254 (https://doi.org/10.1515/pac-2012-1204)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/q2/"
}