Worse than Even - more on probability descriptions

Following up to this post on what do DC should certain descriptions have, I found the original posts I was thinking of and so revisit this and convert to the 5e bounded accuracy system.

I was recalling the data visualisations done by u/zonination in 2015 on reddit which was building from government research by Sherman for the CIA. Pulling apart the 2019 survey data we can show the percentage probability that respondents assigned to various words. I have re-ranked them most to least probable.

Here the range on each bar is the inter quartile range - 50% of responses fall within this range. Some words are narrowly understood - about even means 50% with no range for most people. Some have a broad range meaning they are less clear - we believe and we doubt being to good examples with a 20% range.

Taking these and combining with the guidance from the 5e DMG that the DC of a 'about even' task should be DC15 we end up scaling all this to have a maximum at DC 30. This fits exactly to the bounded accuracy system.

What is very interesting to me is the steady trend of probability descriptions from 'certain' to 'even chance' and then a jump to 'probably not'. All is well until you hit 50-50, then once things go past that it immediately jumps to 1-in-3 and gets worse from there. Here are the ranges expressed as DC for 5e.

Probability Word	High DC	Mid DC	Low DC
Almost No Chance	31	30	29
Highly Unlikely	29	29	28
Little Chance	29	28	26
Improbable	29	27	24
Chances are Slight	28	26	25
Unlikely	28	25	22
We Doubt	28	25	22
Probably Not	26	24	22
About Even	16	15	15
Better than Even	14	13	13
Probable	13	11	8
Probably	13	11	8
Likely	11	10	8
We Believe	11	8	5
Very Good Chance	8	6	4
Highly Likely	7	5	2
Almost Certain	4	3	2

I am not convinced this is more useful than our previous example so for comparison, here is that rescaled for 5e also.

Descriptor	% span	d20 span	DC
Almost no chance / remote	1 to 5	1	30
Very unlikely / highly improbable	5 to 20	4	25
Unlikely / improbable (improbably)	20 to 45	9	18
Roughly even chance / roughly even odds	45 to 55	11	15
Likely / probable (probably)	55 to 80	16	7
Very likely / highly probable	80 to 95	19	3
Almost certain(ly) / nearly certain	95 to 99	20	1