I don’t like it written that way either, and it always seems like the type of number you put on a slide for a head of sales or something. It rankles because:

- it implies that error could be increased n-times, but a 15x _increase_ in 9% error would be an error rate of 135%, which is nonsensical.

- a reduction from 90% error to 20% error is clearly a bigger improvement in rightness to a reduction from 9% to 2%. One is “almost all wrong to almost all right”, the other is “more right”, but they are both a 4.5x reduction in error which means that the 4.5 quantity doesn’t have a constant meaning.

The answer is something like log odds ratios, but that introduces the additional need for a reader to know what that is, and that would be unusual.