Statistics: Alternate Variance Formulas

[haappyone]

noone else can teach like you . You are a great teacher. keep it up. It's really suprising to see three dislikes for this video.

[THE16THPHANTOM]

big boy mathematics.

(i think a kid in primary school can do this if they watched these videos.)

[MrBonesigh]

thank you!!!!!!!

[lizlizlizliz7]

I think I would like to marry you.

[silsilac]

you helped us thanks alot,by sakariye aadan

[silsilac]

good

[silsilac]

dddddd

[SuperRockstar206]

I dont understand cuz im only 11

[THE16THPHANTOM]

@SuperRockstar206

doesn't matter how young you are you can do this if you can add,subtract, divide and multiply, and watch the play list. long live you-tube...and this guy that does this.

[dshnig]

wait if the average of each X(sub)i equals Mu, then how did you cancel it out with the denominator N? shouldn't it still remain 2x Mu squared divided by N?

[chrisisretardedxD]

oh thank you so much!!!!!!seriously i have a stats final in 7 hours and you helped me out so much thank you!!!you make it so easy!

[MrNicorodriguezD]

I've got a question... If I have the size of the population, but I just need the variance of a sample, e.g: (N=60, n=10), then I should use n-1? thnx!:)

[rebel7332]

Thanx, I like your way of teaching

[MissDJ]

i hate numbers

[durumsemolina]

thanks Sal!

[renj3000]

can you do a video for standard deviation for group data thanks

[Enviousful]

Shouldn't also been ... -2*u divided by N + u ..., because it is the whole formula divided by N?

Hoping an answer

[xAliceDollyMisfitToy]

I have to take statistics this upcoming semester. I know nothing about it since I've never taken anything related to it and watching this video scared me to death...haha...wow...I really hope it's not as hard as it looks. I have a feeling I'll be coming back to your videos soon.

[crispy82185]

@xAliceDollyMisfitToy i have to take statistica in an upcoming semester i have feeling i will too

[DiamondApple100]

AMAZINGGGGGGGGGG THANKS!! YOUR THE BEST~~~! ... your teaching a student who had no idea of what math was ! NOW i totally get it! this will help because im taking a stats course in two years. .. Question- is this all the possible work i would see in statistical math?

[deadboy000]

i failed on statistics -.-" lol

[antikorean]

This guy is awesome! I have been looking for how to work this formulation out!

[hsktoadftw]

i love you. ohmygod

[Ihatenicknames1]

This is very helpfull, I watched all the statistics videos and love the topic now

Thank you so much, you have no idea how much you have helped me

[3runrob]

if you wanna know how many videos youtube has or many other facts about youtube click on my channel

[yynotx]

i still get a small thrill from an unanticipated cancellation--living large!

[aozcakir2]

watched on Jan 04,

Thanks

[dasboot356]

I always understand what Sal is doing (and I watched around 40 ones, yet) but at 4:20 I don't get it. Please help me here, where is the sum of 1 in the numerator come from? It looks like conjuring up an N for cancelling out with the N in the denominator...

Thanx for helping me.

[konopong]

mu squared times the sum of ones in the numerator comes from the fact that you add mu squared N times, which is simply Nmu**2. After you square the original variance numerator you need to sum each of the three terms from 1 to N.  Hope this helps.

[BurningBright4ever]

what he is doing is summing up 1, N times (1+1+1+....N) and then multiplying by mew squared. An alternative could be just summing mew N times (which would have been easier to understand). What this would look like is replace 1 with mew sqared. (and there would no longer be a need to multiply by mew squared).

[backstudy27]

This is beacause the sigma applied to everything inside the brackets, including the constant u. (u is a constant because there is no x-sub-i to contribute to the sum).

[crlfdpta]

@dasboot356 lots of times the proprieties of a sum are the same as the integrals.the 2nd term has a variable so you put the sum of Xub i times the constant 2*mew .the 3rd term has only the one because its all a constant, it has no variable!

[yynotx]

I you are rerferring to the 3rd sigma term at 4:28--

the 1 is from moving the moo (or "u") to be a

coefficient fo the sigma expression

[ninjajesus81]

@yynotx I still don't understand why the third sigma term is multiplied times 1. Why would that cause the moo to become it's coefficient? And if you're multiplying it by 1, why even put the 1 there?

[InMooseWeTrust]

What is the point of doing this? I was confused enough with the standard formula.

[shazaduh]

The standard formula requires that all of the samples be involved in each new calculation. This is a very inefficient use of computational power and memory, but with above formula, running tally is kept while moving through the signal. This is good for microprocessor or FPGA in DSP design.

[orpheus1664]

I highly reccommend this guys videos, he's VERY good at explaining things simply, which is not easy when stats is concerned :-D

[Shazaaming]

That's really interesting...

Thank you.