Ok so our population variance is 20, but as you eluded to, our min and max doesn't vary by 20 and 20 is our squared value. So what does 20 tell us about the data? We cant say the variance of the population is 20 because that makes no sense when your min is 1 and max 14. Do we take the Square root of 20? I dont understand why 20 means anything, even though i understand how you got it. Can you please elaborate?
One of the reasons is that squaring preserves differentiability of the function at 0 and second reason is that it is more sensitive to so called outliers.
Well, given that it's squared and not abs, a variance of four, could be four data points all one away from the mean but it could even be three data points exactly on the mean with one point two away from it. It's debatable as to whether that is skewed: maybe one value being far from the mean is as 'variant' as four values being half the distance, who's to say? It also has definite pros, for example, the variance is equivalent to the mean of the squares minus the square of the mean. A second
So that you always underestimate the sample. If you look at the population data and the sample data means, you d find very different results so 1/n-1(N-1) will always get you as close as possible to the pop data by underestimating. You can prove this yourself if you use the same pop. deviation equation without the -1 and seeing how much the sample deviation and pop differ. then try it with -1. Hope this helps.
Hi human family please can someone clarify variance for me in laymen's teems. English is not my first language. I wanna be able to use that term for my English exam. Thanks
Khan, why do you put a SQUARE to the difference? You explained it's to make it a positive number. But you can simply put an ABSOLUTE sign around it instead of SQUARE. My problem with SQUARE is that, it exaggerates large differences (e.g. 5->25) but ignores small ones (e.g. 0.5 -> 0.25) so the result is skewed. I know there must be an explanation. Do you know why?
mhtinla extending the mod function into continuous probability functions is way more difficult than simply using the square function. We choose to use the easier option
Using absolute doesn't work in all cases. It might give same variance value for different distributions. Please look at: mathsisfun . com/data/standard-deviation.html
"I dont wanna date this video too much theres 36 of us now".....LMAO you still dated the hell out of the video. I highly doubt the number of Khan Academy employees is anywhere near 36 today.
This is high school stuff.... Just standard deviation and the mean. I am in high school and we do more complex calculations that this, this is only the basic.
Omg 😮 I got excited because I understand it omg
khan academy gets me lit bc it always gets me through college hw
Ok so our population variance is 20, but as you eluded to, our min and max doesn't vary by 20 and 20 is our squared value. So what does 20 tell us about the data? We cant say the variance of the population is 20 because that makes no sense when your min is 1 and max 14. Do we take the Square root of 20? I dont understand why 20 means anything, even though i understand how you got it.
Can you please elaborate?
One of the reasons is that squaring preserves differentiability of the function at 0 and second reason is that it is more sensitive to so called outliers.
Great content, do you have a link to the calculator emulator you're using?
Thank you so much! I was very confused before about what the variance tells us but it is very clear to me now! :)
so why does is the rule the way it is? what does each part of the formula/process represents?
Shouldn't the answer for sample variance be 25? As the formula denominator is (N-1) not N?
N = is for population
n-1 = is for sample
😊
WOW Thank you so much for helping me!
You need easy explanation, welcome to khan academy
Thank you sir. It really helps me for my exam
Thank you, sir!
So clear!!!
Well, given that it's squared and not abs, a variance of four, could be four data points all one away from the mean but it could even be three data points exactly on the mean with one point two away from it. It's debatable as to whether that is skewed: maybe one value being far from the mean is as 'variant' as four values being half the distance, who's to say? It also has definite pros, for example, the variance is equivalent to the mean of the squares minus the square of the mean. A second
So it's the squared distance away... so what do I wanna do with it, take the square root?
Very good and concise
God bless you
Thanks well understood
Arigatou Gozaimasu!
That was very helpful! Thanks
That was great, that you. But, what is the answer to the last one -- 20/5= 4?
I dont need the calculator either but I always have one handy beacause math equations make my head spin sometimes
Is the formula for population variance?
THANK YOUUU KHANNNNN
hello. Can we use this for grouped data ?
thank u sir.
why do some sample variances subtract 1 from the denominator?
So that you always underestimate the sample. If you look at the population data and the sample data means, you d find very different results so 1/n-1(N-1) will always get you as close as possible to the pop data by underestimating. You can prove this yourself if you use the same pop. deviation equation without the -1 and seeing how much the sample deviation and pop differ. then try it with -1.
Hope this helps.
The calculator determines n minus 1 to be 4 variance being 25.
Hi human family please can someone clarify variance for me in laymen's teems. English is not my first language. I wanna be able to use that term for my English exam. Thanks
You should explain how to understand girls!
boy😂
Well deym 8 years but still funny
Never been able to understand this thing back when i was in College o_0
He's talking about POPULATION variance.
Khan, why do you put a SQUARE to the difference? You explained it's to make it a positive number. But you can simply put an ABSOLUTE sign around it instead of SQUARE. My problem with SQUARE is that, it exaggerates large differences (e.g. 5->25) but ignores small ones (e.g. 0.5 -> 0.25) so the result is skewed. I know there must be an explanation. Do you know why?
mhtinla extending the mod function into continuous probability functions is way more difficult than simply using the square function. We choose to use the easier option
it's really sad that i am now in grad school, just starting to understand this! 😂 thanks
Using absolute doesn't work in all cases. It might give same variance value for different distributions. Please look at:
mathsisfun . com/data/standard-deviation.html
I love you. That's all i need to say.
haha got the same feeling
me watching this in preparation for the next sem ..
pop mean
"I dont wanna date this video too much theres 36 of us now".....LMAO you still dated the hell out of the video. I highly doubt the number of Khan Academy employees is anywhere near 36 today.
frist
This is high school stuff.... Just standard deviation and the mean. I am in high school and we do more complex calculations that this, this is only the basic.
Hah, "frist".
Obviously not standard deviation.. as it is squared. Not sure why you're even saying what you're saying. Of course this is basic, what did you expect?