I don't see a problem with them expressing the ratio as a decimal since it becomes a simple multiplier of the original file size 38GB x 0.3.
But it's downright misleading to show the vertical axis from something other than 0.0 to 1.0 when comparing ratios. They start it at 0.2. In reality, LZJB is saving 50% of the space whereas gzip saves 70%. But a naive glance at the graph implies gzip look roughly 3 times smaller/better than LZJB.
Classic "How to Lie with Statistics" stuff.* I would have expected better from an "analytics" database.
But it's downright misleading to show the vertical axis from something other than 0.0 to 1.0 when comparing ratios. They start it at 0.2. In reality, LZJB is saving 50% of the space whereas gzip saves 70%. But a naive glance at the graph implies gzip look roughly 3 times smaller/better than LZJB.
Classic "How to Lie with Statistics" stuff.* I would have expected better from an "analytics" database.
* Not saying they intend to lie here but it's representative of the classic text https://en.wikipedia.org/wiki/How_to_Lie_with_Statistics