# Proportion explained variance

Proportion explained variance gives the ratio of explained variance and target variance. Explained variance is the difference between target variance and variance of prediction error.

## Proportion explained variance at a glance

• Description: Proportion explained variance is the ratio of explained variance and target variance. Explained variance is the difference between target variance and variance of prediction error.
• Default thresholds: Lower limit = 80%
• Default recommendation:
• Upward trend: An upward trend indicates that the metric is improving. This means that model retraining is effective.
• Downward trend: A downward trend indicates that the metric is deteriorating. Feedback data is becoming significantly different than the training data.
• Erratic or irregular variation: An erratic or irregular variation indicates that the feedback data is not consistent between evaluations. Increase the minimum sample size for the Quality monitor.
• Problem type: Regression
• Chart values: Last value in the time frame
• Metrics details available: None

## Do the math

The Proportion explained variance is calculated by averaging the numbers, then for each number, subtract the mean and square the results. Then work out the squares

``````                                  sum of squares between groups
Proportion explained variance =  ________________________________

sum of squares total
``````