Merge pull request #193 from tomgwasira/patch-1

Update evaluation.mdx for correct computation of CER.

Author: Deep-unlearning

chapters/en/chapter5/evaluation.mdx

@@ -126,12 +126,12 @@ In our example, we have 1 character substitution, 0 insertions, and 3 deletions.
 $$
 \begin{aligned}
 CER &= \frac{S + I + D}{N} \\
-&= \frac{1 + 0 + 3}{14} \\
-&= 0.286
+&= \frac{1 + 0 + 3}{17} \\
+&= 0.235
 \end{aligned}
 $$
 
-Right! We have a CER of 0.286, or 28.6%. Notice how this is lower than our WER - we penalised the spelling error much less.
+Right! We have a CER of 0.235, or 23.5%. Notice how this is lower than our WER - we penalised the spelling error much less.
 
 ## Which metric should I use?