ANOVA 1: Calculating SST (total sum of squares) | Probability and Statistics | Khan Academy
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- เผยแพร่เมื่อ 11 พ.ย. 2010
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Analysis of Variance 1 - Calculating SST (Total Sum of Squares)
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I havent seen your videos in so long but I was curious about some statistical techniques and TH-cam's search results didnt have you even top 10, but I remembered you being caring and knowledgeable in your videos and I am glad I looked you up specifically. Time to look through the rest of your ANOVA videos. Thank you so much!
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Finally I have an intuitive sense of why computing the sample variance of a dataset involves dividing the sum of squared distances from the sample mean by N-1. Thank you.
Great video (as always with Khan Academy) BUT the mean of means in general is not equal to the grand mean. For them to be equal, you need to have the same number of data points in each group. Otherwise, you must calculate the grand mean by simply averaging together all the values in all the groups.
This is great, very clear and informative!!!
You make everything so simple! I wish you could teach in Swedish terms but this is already Sooo helpful God bless you
Get an internship and translate everything in Swedish...
you explained it very well ^_^ .. thank you!
I recall that for chi square, the degrees of freedom was (m-1)(n-1). I don't understand why this should be different.
Here is only 3 columns
D.f for this specific case (SST) which he didnt use any other types of mean, but the mean of all the data points combined divided by the number of data points which is 9. Therefore d.f is just n-1. The reason behind this is just that if you know the mean, it simply means after knowing 8 data points, the 9th one has to be an exact number which you could calculate to match with your mean, hence only 8 numbers are free to become any numbers, while the last number isnt free. This is also why you later will find (m-1)(n-1), I dont know if the formula is correct, but by my intuition this is also showing you something similar, when you know the mean of each of the sets individually, that takes away some of the freedom to variate the numbers.
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Till date, the best coverage of ANOVA
This is so much better than my professor's lectures.
sir is it possible to answer this qs with Combined mean ??
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every nice video. Today is my FIRST day to understand SST!!!!!!!!! THANK YOU ,SIR!
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What would be great for both the regression and anova series would be for Sal to show how they both apply CLT, since they both are dependent on CLT but how is not intuitive.
Sal has been there for me when my professors fail at doing their job.
If nobody got me, I know Sal got me
In my exams at uni we often have to fill in the blanks of the anova summary table. is it possible to calculate SStreat when you only know DFtreat, DFerror, and MSerror?
Disclaimer - the "mean of means" (average of multiple means) is only = to the grand mean (average of all data points) when each group has the same number of data points (in this case they all have three).
please make a video about how to calculate wards method
very informative
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Shouldn't you be using the greek letter of "m" for the mean and not the letter "x"? The letter "x" could represent the independent variable and that could be confusing.
Thanks
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Totally lost me at the end there with the degrees of freedom and variance bit. It was scattered and confusing.
degrees of freedom generally just means how many observation is free to be whatever it wants to be given known the mean, in this case there are just 8 observation that could go freely, the last, or ninth number must be a specific number after knowing all other 8 numbers, because of the mean. The case with variance is because if you play around the SST formula algebraically you will find that the formula is exactly the same as the variance.
@@sixtysixx3933 but in the last video he said degrees of freedom=m-1*n-1
productive talk
You're awesome
can anyone help me with this question Make up a sample of size n = 7 for which the average is −13 (note the (−) sign). Not all 7 numbers
should be identical.
13 years later and I am here 🔥
I have N=20, k=4 (m1=4, m2=8, m3=12,m4=7) and SSB=22. How do i find the value of SSW?
So degree of freedom for ANOVA is (MN-1) whereas d.f. for Chi-squared is (M-1)x(N-1)?
You are really genius Sal. Thank you for all your hard work and efforts in putting across such amazing videos.
I dont know what I'm doing wrong but with data sets of
a = 21, 15, 16, 20 -> mean = 18
b = 6, 10 -> mean = 8
c = 17, 13, 8, 10 -> mean =12
Grand mean would then be All data point/10 = 13.6
But the mean of the means is (18+8+12)/3 = 12.6
Edit: To calculate the global mean out of the mean of means, the means of the samples must be weighed. in My example: (18*4 +8*2 + 12*4)/(4+2+4) -> 13,6
Confused do I divide the SST (30 in this example) by the DF? and that gives me the SST?
Charlie Marie no that will give you the sample variance
HAHA hi Yousif, I very slowly realized this but thank you
You should start your own university. I’ll attend classes that i’m sure will make sense 99% of the time.
whats is the mane of progam the teacher use.
The more i watch his videos the more i hate my prof at school .. lol
I think the title should be Calculating TSS ( Total Sum of Squares )
somehow it doesnt work.
I dont understand m.n-1 degree of freedom
SST was not equal to X double bar, you were not able to prove it then you ended to computing df
How 1+4+9=14???
u saved my life away from singko HAAHHAAH
without doubt the worst way to calculate SST.