Sample standard deviation and bias | Probability and Statistics | Khan Academy

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[@arianacareymariahgrande3582]

2:48 - 3:01 nobody: Sal: *HOW MUCH*

[@ravenkask8419]

LOL

[@hudsonlind9513]

Sal has become the voice of math for a whole American generation

[@ProsaicPudding]

But how DO you find the unbiased standard deviation??

[@designersdelight]

Thumbs up! absolutely thrilling to watch a true and great muslim doing work for humanity

[@SaraphL]

Good guy Sal makes new videos on topics we already know just so we can watch them in 720p.

[@1029blue]

I love math, specifically statistics! :) Thanks for making these videos to show people that math can be mastered *and* fun!

[@micery]

Thank you for your help! I have midterms tomorrow! And for fun... 2:49 seizure :)

[@Pazer885]

Excellent example.

[@santoshdc123]

Thanks for the link

[@Kashif_Javaid]

I noticed this new trend now where Sal has done these calculation ahead of time.

[@prettyo.1385]

but how do you get those starting samples? in my homework my teacher jst gave me 2 columns of 4 numbers, one for "the trucks' age" and one more for the "dollars spent on reparations of the past year" im screweddd D8

[@DoughyDoughBoi]

SHOUTS OUT TO KHAN!

[@gmvsea]

my memory is fuzzy here, but i seem to remember that the expected value of the sample standard deviation approaches the population standard deviation---or is it the expected value of the sample variance approaches the population variance?---why not just use absolute values instead of squares for computing the standard deviation directly---wouldn't that avoid the non-linearity problem?---of course, i suppose since variance it's defined by squaring the differences...

[@nixhj3848]

why was 1 taken from 8 to divide my 7?

[@andrewzhu5294]

It is because the sample standard deviation has the tendency to be an underestimate of the actual standard deviation. By subtracting 1, it allows the sample standard deviation to be more accurate (less biased).

[@nathan4659]

@@andrewzhu5294 THANK U

[@viewsfromsameer]

anyone know where to get that calculator? i really need it thnks

[@JDoubleOP]

At your service, yw :-)

[@nocturnalvisionmusic]

Awesome video and like 500 (11/28/23) 🥳💓

[@ahmedemary3805]

what is bias?and why is Sn-1 is called unbiased?

[@santoshdc123]

Where we can buy that calculator ?

[@ghulamsiddiqui3659]

Santosh Dangi amazon

[@topgrain]

Still too much terminology that all sound the same. I get the questions wrong because of that.

[@lalaithan]

Mnemonics help me with similar terms.

[@Majora09]

you sound like wowcrendor... might be that it's 2 am

[@paulramones6895]

I know I'm not the first to ask, certainly not the last, but what program is the calculator?

[@Lalala4whatever]

Why was the 1 taken away from the 8?

[@winexhd9373]

Hey, not sure if you have this question answered. I actually struggled with this too, when it comes to variance there are two types. Sample variance and Population variance. Really, the only difference between the two is in Sample variance, if n is the size of data set, then the denominator is n-1 (instead of n). Since Sal had a sample data set (not population data set) he applied Sample variance formula to calculate the variance. You may ask why there is a difference between the sample variance and sample population, why can't it just be as simple as mean where the formula does not change at all - well there is actually a good reason for it. Thing is, the mean is very 'special' because the mean of a sample is a good estimate for the mean of population. Meaning if you take the mean of a sample and then compare it to the mean of the population, then they will be very close. Unfortunately you can't say the same thing about variance. You can actually try this on your own by the way! If you use the population variance formula for a sample, compute its variance and compare it to the variance of the whole population - you will always be off by some amount. It just wouldn't be a good enough estimate sadly, and what is the point of calculating variance of a sample if it is not even close to the variance of population? So someone decided to change the formula of sample variance such that it gives a variance value much much closer to the population variance.

[@avadakedavra7193]

Hello there

[@Lauderdalesfinest954754]

Cube Bass..! lol

[@Siouxjin]

Lol, the "Math-bot" got an error of some kind

[@laurellion3567]

Maybe I'm the dummy here, but those numbers don't add up to 48 for me.