[hinkley]

Most graphs with deltas are comparing multiple deltas, not a single delta, which results in misrepresentation.

By screwing with the origin you can make the alternative that saw a 6% reduction look much more compelling than the one that achieved a 4% reduction, when in fact it's probably only slightly more compelling.

[stefco_]

Yes, I agree that these are often abused tactics. Just saying they have their uses. The fundamental problem is graph literacy.