Percentages

huh, this feels pretty well established here in sweden: whenever people talk about stuff like elections it's consistently percentage points

Can't believe nobody has linked the relevant xkcd yet

Having two possible outcomes does not mean it's a 50:50 chance.

"So if I aim the arrow at the 1cm square from 100m away and shoot, I either hit it or I don't. So basically I have a 50% chance of hitting it."

That's not even a stat question, it is a english question. It is an increase by 80% not to 80%
Statistics only come to play to figure out our new chances.

In game design, it has to be stated whether it’s multiplicative or additive. Sometimes a logarithmic function is used as well, with increases in efficiency as 1 / ( 1 + bonus ). This allows you to always add more bonus, but there’s diminishing returns.

When my son was about to be born my mother in law caught wind that we didn't plan on circumcising (before researching it I mostly felt it was just strange to do cosmetic surgery on a newborn) but her argument was mostly parroting the 50% reduction in this that and the other disease, missing the fact that it was going from a 0.5% chance to a 0.25% chance, but of course introduced new risks by nature of being a surgery.

Naturally after looking more into it I learned just how bonkers circumcision is so I was far more cemented in my position

I play video games; I need to know if the percentage is additive or multiplicative.

"+100%" looks pretty good until you see what "×25%" actually gives you.

Funny thing is this is a language issue, not a math issue.

It's really pretty simple - if something increases by 80%, you add 80% of whatever it already is... one dollar becomes $1.80... one percent becomes 1.8 percent.

Most people don't understand it because they've seen it done wrong so often, the wrong way seems right.

I work in a place full of statisticians, and we've had to unfortunately have numerous conversations with some of them about the difference between "a decrease" and "a decrease in the rate." Apparently "it's increasing slower" isn't clear enough for some.

I've always wondered how to disambiguate multiplication and addition of percentages. I guess that's what percentage points are for?

Difference between increase of x% (old percentage + old percentage * x%)% and increase of x percentage points (old percentage and x)%

So you're telling me there's a chance?

well it's ambiguous. Its also a sloppy way of expressing an increase by 80 percentage points.

Wrong: I had a 1% chance, and I doubled my chances. Now my chances are 101%.

Right: I had a 1% chance, and I doubled my chances. Now my chances are 2%.

Wrighongt: I had a 1% chance, and I doubled my chances. Now my chances are 3%, because I'm a lucky person.

People got this wrong about inflation as well. In 2020 there was actual deflation, and in 2021 there was very minimal inflation, meaning prices were still largely lower or similar as 2019. Then we saw 9% inflation in 2022. Total inflation in 2024 vs the 2019 benchmark was around 15%. Or 3% average per year, which is barely over the baseline. People just hear 9% inflation, completely missing the fact that this was a YoY number relative to the Trump recession.

That's why when presenting numbers at work, we always distinguish a movement of X % (percent) from a movement of X ppts (percentage points)

Dark Souls cleared this up for me real quick.

I know all this. I play DPS!

In the same vein, if the volume on your phone is on 1, and you increase it to 2, it has increased by 100%

Why lying with maths is so easy, the average person, even in developed countries is practically innumerate (massive hyperbole, but the fact lying with numbers is easy, still stands)

Did this turn into an /iamverysmart thread ?

Even more confusing when you hear that the odds of catching a disease have increased by a %. In many ways odds can be more intuitive, but we're so used to working with simple probability that it's a total nightmare to wrap your head around at first.

Convert percentage to fraction, i.e, 80% become 0.8 Then multiply with initial value

If it says 80% more use initial + (initial*80) or simply initial*1.8

Or if it says 80% less, use - in above calculation or multiply by 0.2

I find percentages more neat when used as fractional number Edited to escape the multiplication symbol

hopeful-weirdo just needs to be told to consider what increasing by 500% means and it'll click.

The different ways in which numbers slide up, down, sideways, diagonally.

Is the example in the post part of the fifth type of arithmetic?

1. Addition +
2. Subtraction -
3. Multiplication x
4. Division /
5. Modulo %

The first time I learned about modulo as its' own branch of arithmetic was long out of school already, I had only hazily heard of it, on a PBS Nova documentary in the 1990s about Fermat's famous theorem and when it was proven after centuries of failed tries.

I think it's ambiguous and the 90% actually makes more sense. If you increase something by 5m you are taking the original value and adding 5m to it. For multiplication you should probably avoid the word increase and say scaled by instead. 10% scaled by 180% is 18%.

Ever seen girl math?

"If I preload my Starbucks account with $25 and I go to Starbucks the following week, my order was free."

"Spending money abroad doesn't count because it's a different currency."

Things aren't mathing as they should.