Statistical significance testing

As mentioned in a recent [paper](https://aclanthology.org/2021.acl-long.566.pdf) about evaluating MT approaches (and probably other sources too), statistical significance testing can be used to confirm that one method is superior to another, saying that 'it remains one of the most cost-effective tools to check how trustworthy a particular difference between two metric scores is."

We could possibly use the Wilcoxon signed-rank test (implemented in [scipy](https://docs.scipy.org/doc/scipy/reference/generated/scipy.stats.wilcoxon.html)) or another similar approach.