R-squared is a statistical measure that represents the proportion of variance for a dependent variable that's explained by an independent variable or variables in a regression model. In the context of toxicology, R-squared helps in quantifying how well the predictions of a model match the actual observed data. An R-squared value ranges from 0 to 1, where 0 indicates that the model does not explain any variability of the response data around its mean, and 1 indicates that the model explains all the variability.
