We use probabilistic words such as "likely", "unlikely" and so in normal conversation. I would like for these rather vague notions to be given some mathematical precision. As a way of doing that I've arbitrarily assigned values to them as follows (let P = probability)
- Certain: P = 100%
- Highly likely: 100% > P $\geq$ 75%
- Likely: 75% > P > 50%
- 50-50: P = 50% (may be)
- Unlikely: 50% > P > 25%
- Highly unlikely: 25% $\geq$ P > 0%
- Impossible: P = 0%
Are these acceptable values or not? Why?
Muchas gracias.
The correct interpretation of a phrase like "highly likely" depends heavily on the context of the statement. You won't be able to make a simple translation table like this that gives accurate results across all or even most statements.
I'll add one comment: People usually overstate their confidence about pretty much everything, and especially when dealing with highish probabilities. If someone says a result is 90% or 95% or 99% certain then the true probability is often much lower. So even when people literally make a precise numerical claim about probability, I still wouldn't recommend trusting it!