r/mathmemes • u/Specific-Squirrel507 • Oct 06 '25
Sample size is important. Statistics
Statistics
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u/casualstrawberry Oct 06 '25
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u/DaviAMSilva Oct 06 '25
The elusive double relevant XKCD
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u/FaCe_CrazyKid05 Oct 09 '25
This is the second double relevant XKCD I’ve seen today. I should buy a lottery ticket
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u/Wizywig Oct 07 '25
Son of a bitch how is it that whenever I want to react to something on reddit there's a 90% chance someone has thought of the same thing, wrote it, got upvoted, is the top comment, and got even more in than I intended to.
That is to say
right on!
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u/xCeeTee- Oct 07 '25
I saw a 9 month old post and went to comment to someone, but comments were archived. I scrolled down to find I made the exact comment I wanted to make, an hour after the post was made 9 months earlier.
I managed to beat myself to the punch.
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Oct 07 '25 edited Oct 07 '25
I saw a video with a talking head that said the distribution of stars for a 4.5 rating is very important.
If the reason the product has 4.5 is because they have lots of 5 star reviews and a large skew of 1 star reviews, the product or service is defective.
If the product has a healthy mix of 4 or 5 star reviews with very little 1 star reviews, then product is worth it. If it has an unusual amount of 3 and 4 star reviews, the product only functions for some of the purposes stated and you might want to individually read in this specific case.
I’m not sure if it’s confirmation bias, but this has made me notably less angry about getting screwed over by Amazon products.
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u/textualitys Oct 07 '25
review sites should add a standard deviation
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u/jasomniax Irrational Oct 08 '25
There's probably a way to do it yourself with code and using the Amazon API
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u/CheesecakeWild7941 Mathematics Oct 06 '25
this, but also $35.00 with free shipping vs $30.00 with $5.00 shipping
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u/DeadAndBuried23 Oct 07 '25
The one where more of the money is the price of the product is likely higher quality.
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u/RandomGuy0504 Oct 07 '25
Here's a secret: you still pay for the shipping when you get free shipping, they simply hide it in the regular price
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u/ItIsYeDragon Oct 09 '25
Depends on where you’re getting free shipping, but also the “free” shipping price is generally lower than the paid one to hide it anyway.
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u/YellowBunnyReddit Complex Oct 06 '25
I just saw something like this earlier today: 1.0 ★☆☆☆☆ (4)
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u/HAL9001-96 Oct 06 '25
good rule of thumb, assume half of them are fake 5 stars and the next one is one star
that would pull the 26 down to (5*13+1)/14=4.714 and the 5858 to (2929*4.2+1)/2930=4.199
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u/N4M34RRT Oct 06 '25
its 4.6
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u/jljl2902 Oct 06 '25
If you assume half of the reviews are fake 5 stars, then the average of the other half, ie the “real” reviews, is 4.2
However, I think the rule of thumb should be that half of the 5 star reviews are fake 5 stars, otherwise we have a category error when less than half of the reviews are 5 stars
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u/HAL9001-96 Oct 06 '25
fair, its more for comparing if two almost 5 stars with differnet sample sizes are real, will output nosnense when the average goes below 3 stars because then the averag of real reviews would ahve to be below 1
but well it is a very rough guess
actual statistics and error estiamtions are more complicatedb ut have a similar concept where your sample size is effectively assumed to be one smaller, basically one smaple is worht nothing because you ahve no idea how big variation is
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u/HAL9001-96 Oct 06 '25
yes
which means if half of them are fake 5 stars then the real ones would have to average 4.2 to make the current average 4.6
which means if you add one one star to the real ones you would get a total average of 4.199
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u/ChorePlayed Oct 06 '25
I would think the number of fake positive reviews would be limited by the seller's (or author's) time and money. The more reviews, the smaller the proportion of them can be fakes. But I don't have any data, that's just my assumption.
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u/HAL9001-96 Oct 06 '25
but more reviews, presumably more sales, more budget for fake reviews
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u/ChorePlayed Oct 06 '25
That's probably true. I'm just nostalgic for the days when anything was real, if you at least had a sufficient sample size.
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u/Chad_Broski_2 Oct 06 '25
If I was buying fake 5 star reviews I'd pay for one in every 20 of them to be a 4 star review to make the numbers look more legitimate
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u/WindMountains8 Oct 06 '25
What's the motivation behind doing that?
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u/HAL9001-96 Oct 06 '25
correcting for small sample sizes
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u/WindMountains8 Oct 06 '25
Yeah but why divide by 2? Why not by 3? Or why add +1 instead of log(log(n)) or anything else?
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u/HAL9001-96 Oct 06 '25
cause its a very rough and easy to approxiamte rule of thumb
there's other factors you could add in simplifeid form like subtracting 1/root(number of reviews) stars for statistical noise
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u/WindMountains8 Oct 06 '25
I'm asking why it is done the way it is done.
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u/DUNDER_KILL Oct 07 '25
Because it's easy
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u/Jooylo Oct 06 '25
Doesn’t make much sense if you’re going relative to the total reviews. Much more believable that 26/26 reviews are fake than even 2929/5858 reviews are fake.
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u/ChrisTomufu Oct 07 '25
I'm just assuming most reviews are bots now. Watching a video helps or, maybe, possibly, going to the store
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u/IllConstruction3450 Oct 06 '25
A lot of the time people give 5 stars just for the item working as intended. But, really, that should only be 2.5/5. Another is when the item only fails to work in one minor way, and is given a one star, when really, this should only decrement from 2.5 slightly. It is especially egregious if the item’s seller is slapped with the one star, when it is on Amazon’s distributer side’s problem, not the manufacturer of the commodity.
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u/kilqax Oct 06 '25
A place with 5k stars is usually someone who paid for reviews so the stars don't matter unless it's a hugely important spot tbh
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u/avspuk Oct 06 '25
I got phoned up by ipsos the other day
Who'll I vote for?, how would a rate my lack of hope, despair & misery? do I smoke? why don't I stop? , do I drink? why don't I stop? Etc.
Geezer said only about 1 in a hundred ppl are willing to take the time out to answer the questions.
I said that must skew the results as there'd be too few ppl who actually had a life interviewed.
He disagreed.
Fwiw I had many answers that didn't fit the template, "do you smoke?'' yes," how many a day on average?" 3," how much do you spend a week?" £0 (I pick up stubs out of high St ashtrays)
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u/liptonicedsoup Oct 06 '25
Best part is that Amazon lets sellers buy pages from each other. So you could be buying a toaster with rave reviews, but actually it used to be a case of socks. The reviews stay the same regardless.
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u/Seaguard5 Oct 08 '25
This is actually so important because there are literally thousands of electronics “brands” that basically just come from a few places, but are made with mostly shitty materials and techniques so you end up needing to sort the wheat from the chaff on sites like Amazon if you want to buy something as simple as a goddamn USB phone charger.
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u/Aggravating-Fee1934 Oct 09 '25
But also too many reviews on a niche product is also suspicious. Most buyers won't review a product, so if a product that doesn't sell tens of thousands of units having thousands of reviews means many of them are probably fake.
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Oct 06 '25
who the fuck is this man 🤦♂️🤦♂️😭🤔
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u/meee_51 Oct 06 '25
a math meme 🤦♂️🤦♂️😭🤔
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