No, that's dishonest. Probabilities are already ratios between magnitudes (desirable vs. undesirable outcomes), so when comparing them you should be subtracting them, not dividing them. A relative increase in probability of 15% doesn't tell you anything if you don't already know the base probability. Also, why go for the 15%? You could also say that the loss probability is reduced by 2%. But I guess you don't get a nice juicy number that way.
One number never fully captures the reality. If I have a net worth of 1 penny and I earn a second penny, it is 100% true to say I've doubled my net worth. It also doesn't tell the full story.
If a coach can take an action that would move the win probability from 0.01% to 1%, it would be malpractice to not do so, and correct to say they've increased their win chances by a factor of 100. It's also correct to say they're probably going to lose.
I think you're using a restrictive and non-standard interpretation of percentages. They can be used to convey overall probability, but also a change in probability. Only allowing one usage is just a communication deficit.
Not in that particular case, because no one would believe in an increase of 100% (although it would still be preferable to say that it doubles your chances of winning). But if you're at a slot machine and you can put in an extra dollar for a 10% extra chance to win the jackpot, and in fact you chances increase from 0.001% to 0.0011%, would you think that's honest or scummy?
>They can be used to convey overall probability, but also a change in probability.
They can be. They shouldn't be used this way because it lends itself to miscommunication.
Casinos in general are scummy, but I can't fault with the phrasing. What's the threshold at which the world is allowed to use percentages in the way they're meant to be used, without having to be accused of being dishonest?
It's important to distinguish the scummy behavior from the actual statistical practices, as data literacy helps people see through numerical slight of hand.
I think you are backwards from how other people regularly faced with this ambiguity have decided to communicate, given that e.g. finance created a separate term to talk about changes in percentages.
Using that terminology, the win chance has gone up by 160 basis points, which is an increase of 15% from its previous value.
[edit] fixed grammar mistake
> Under completely unrealistic assumptions, G42D8 improves the chances of winning by less 1%. If there is any uncertainty in these calculations at all, then you might even be putting yourself at a disadvantage!
This is implying (without out saying) that a tiny error in e.g. the probabilities of converting a 2 point conversion will make things a disadvantage. After all, what if there's only a 46% (instead of 48% from Ms. Albert's article) of making the 2-point conversion, that must surely lower your win chances by more than 1 percentage point, right?
The answer is "of course not" becuase that just lowers the win probability by a tiny absolute amount as well. In fact this can be seen in the flow-chart that TFA hates so much. The author is either being scummy and disingenuous, or has confused himself by mixing relative and absolute percentage changes.