Final answer:
The ideal values for rwork and r free in crystallography should both be as low as possible, indicating a good fit between the model and observed data, with typical target values below 20%.
Step-by-step explanation:
The ideal values for rwork and r free in crystallography are as follows: rwork and r free should both be as low as possible. These statistical parameters are used to assess the quality of a crystallographic model. A low rwork (the working R-value) indicates a good fit between the observed data and the model, while a low r free (the free R-value) signals that the model predictions are close to the actual unseen data, suggesting the model is not overfitted. The R-values generally decrease with improving model accuracy, and typical target values are below 0.20 (20%) for rwork and slightly higher than that for r free to ensure no overfitting is occurring.