What are the limits of capping ratios to [0-1]? I work with some financial ratios. By construction those variables should be between 0 and 1. However, for some reasons I end up with values &lt;0 and >1. These reasons include :


reporting problems (fat finger errors, unit problems...)
discrepencies between databases
discrepencies due to accounting reassessment


What would be the reasons for me to not cap my ratios to [0,1] ?
In essence, you risk biasing the model by making the values 0 and 1 more likely than they actually are. This may or may not be a significant problem; really only cross-validation will tell you. 

I would go ahead and try it, but compare your results to a different method of filling invalid values, like using the mean() of the valid values plus an extra feature flagging the samples that were invalid. Make sure you cross-validate using a hold out dataset that's been transformed in the same way; you can then select the method that results in the best results of the cross-validation process.