Variance and Standard Deviation: Sample and Population Practice Statistics Problems
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- เผยแพร่เมื่อ 28 ก.ย. 2024
- For more success with variance and standard deviation problems, you can checkout the book I used for reference, Schaum's Statistics Outline - amzn.to/2yeUaDk.
Variance and Standard Deviation are all statistical ways of measuring variation. We'll take a look at how to solve practice statistics problems for sample variance, sample standard deviation, population variance and population standard deviation by hand using just your calculator. In our problem we'll take a look at ages of kids at a birthday party. I also mention how to make meaning of this data if they were points somebody scores in various basketball games. Hope that helps.
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The videos I post on TH-cam are primarily for my own college students, so I usually do not have time to respond to TH-cam comments. But, I'll do my best to respond when I can.
It's funny. Sometimes we stay 2 hours in class watching professor explain how to calculate standard deviation and variance. At the end we don't understand very well. Here, 13 min is more than enough for me to understand and gain confidence. Anyway, thank you very much for the video.
That's so true
Spend time in an hour and a half lecture, and still don’t understand anything, watch a 13 min video or even shorter, and miraculously understand it...explain that
I agree with you
Stephen Kiama e
I seconded you.
I'm in Business Economics & Decisoin Science. Roughly over a month. I just understood your 13 min. video of the sample mean, variance, and standard deviation. Over my professor. I was struggling in finding the mean, variance and SD but i see now that is more simple then what I thought. THANK YOU!!!
That equation looked all kinds of terrifying before you explained what the letters were. I just stared at it in my text book not understanding a single word of it. Now I'm saved. Thank you!
What a brilliant communicator! Totally recommended. Look forward to checking out more of your videos
You just saved my grade. Thank you.
lol funny
Sofia
yh true talk
So where do u school?
You alive?
When you have a full time job plus attend college full time but you find someone willing to give their time to teach others via TH-cam. Thank you for this video, currently taking stats in college.
I had forgotten this simple procedure and I totally couldn't remember
Credits to you
Great demonstration! I would like to be as clear as you are when I ever get to teach!
You can take any kind of statistics help at anderson.kevinnn0@gmail.com
For the variance, you must divide by the total of frequencies. The square of the either of the STDEV.S and .P will not give you the variance which in most cases should be a decimal fraction.
just know that before this I'd used a complicated formula to remember. u saved my time to memorise and understand this thing!!
I got it. 27.2 divide by 4 is equal to 6.8. Anyway, thank you for this video. I learn a lot. God bless☺️🙏🏻
I loved how you described it, I was able to comprehend through your work fast, but how do you do the frequency that goes in the beginning ? Anyone please let me know thanks 🤓
WE ADD ALL THE FREQUENCIES AND DIVIDE THEM BY FIVE(TOTAL NUMBER OF THE FREQUENCIES) TO GET THE MEAN WHICH IS 6.4
sir i really appreciate the way you teaches on this topic, you give more clarity on statistic management concerning variation,thanks
I really needed this lesson before my STAs exam
How did the 27.2 over 4 became 2.607? Did you square root it? How did you exactly got it??
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This was very helpful to understand the formulas. He make it seem very simple to do it yourself.
2.3 * 2.3 = 5.29 , round off will be 5.30 , where did you get 5.4 from ?
how will standard deviation of a set of discrete data change
-when a value that is equal to the mean is added to data
-when a value less than one standard deviation from mean is added to data
-when a value that is more than one standard deviation is added to data?
Sir....plz help me to find the answer of this question :
The mean and standard deviation of a set of 100 observations are worked out as 40 and 5 respectively by a computer which by mistake took the value of 50 in place of 40 for one observation. Find the correct mean and variance
Plzz... bcz this is the most frequently asked question in our exams
It's very helpful, infact when I confuse in my reading (revision) I just visit this clip🙌 🌹🥀💐
So basically there is two ways to solve it depending on what it’s asking?? If it’s asking for sample you have to subtract n-1 & if it’s asking for population it’s just like 5 for example ??
i must say thank you and i so glad i came across your video. i really needed this clarification
Thank you!!! I have been trying to do this for days... I have been trying to subtract the first set of x-x from the second set squared and I was always getting negatives...I was frustrated....
help... i'm cnfused with the z-score equations. how to know if a problem will use population ewuation or sample equafion..?
what is the standard deviation of the data set 30 0 0 ?
Hey the formula is different than the one on the internet without negative 1
bro ur a lifesaver.
if i think this is easy will i do good in statistics class?
Dude i laugh at 3:42 gonna say it happens on class Lmao
real talk
😂 lmao it even frightened me just now because I honestly forgot how to do all this but whenever I took stats in college, I distinctly remember our professor writing out that formula for the first time and the immediate horror
on all of our faces. at first glance, that formula had me rethinking my entire life choices 😂😂
Help please.
A retailer observes that the demand for a popular board game averages 40 per week with the standard deviation of 13. If the seller wishes to have adequate stock 99% of the time, at least how many games must she keep on hand?
Please clear me that why was the denominator in terms of age was n-1 where as for population it us N. Is there any more things in which n-1 is used other than N. Please clear my doubt, anyone
Realy great vedio sir thax for helping
Thank you so much! This was so helpful! I have an exam tomorrow and was really confused before watching this!
it is an interesting demonstration. you make it easy for us. thanks a lot statistic dojo
Thank you for this video. Very helpful.
Thank you
Thank you for the help, great example!!
I don't understand how 2.6 is 27.2/4 squared.
Why is it that when dividing some ppl subtract 1 from it like (n-1) whereas others just divide by n?
I just like this class
why is it n-1
Melissa Rocha I have the same question
now the reason why it is N-1 it is because the first problem he is dealing with only the sample, the equation used is N-1 at the bottom where as a population where if someone sampled everyone then it is divided by N only. In terms of why is sample N-1 that's just something the statisticians have used many years ago.
I don't understand this explanation
If you had the whole population of values, e.g. every single child in the world ("POPULATION"), then you would use N. Since we cannot realistically use the data from every single child in the world, we use a small SAMPLE from that population. It is basically a conventional agreement that since we use a SAMPLE as opposed to the whole POPULATION, then we will introduce an error. Thus N-1.
n_1 is for sample and just n is for population
Thank you for your video. It did help me a lot!
Hi sir I would like to ask at 12:49 why 5.4? I calculate here and it shows that 5.29
Where did you get the 2.6?
Plss reply.
27.2÷4=6.8
Then Square Root of 6.8
=2.607....
thank you so much dear sir
I LOVE YOUR WORK SIR
Thank you so much Sir! Your video was so helpful, but my final answer after i put 27.2/4 in a square root, i did not get 2.607..., i got 1.303840481. Maybe you can help me on how did you get that answer! I will appreciate your help.
he is just amazing
Can you explain the root that 27.2/4 🤔
How did you get 2.607?
How we can calculate the percentage of 5 years old could excite in this class?
Please how did u get this 27,2
so when do we use N as a denominater, and when N-1??
N=all data points(all population) given
N-1= sample of all data points given.
can someone explain the fundamental behind
1) how this figure 2.6 is related to the initial series of 5 numbers?
2) how this 5.4 is related to the same initial series?
what is the usage of these two figures?
Thanks professor
please I need assistance for x bar when calculating mean, the symbol is missing in my computer
ty for this video, i know how to get the variance and standard deviation
Great work ... thank you
Thanks so much, really helpful
Yaaaa good sir and please make more videos on states sir it will help mee sir
Am asking for the interpretation please
Thank you so much
Wherr do u get 5.76? I dont understand that portion
I think this will help me thanks.
Thank you kind sir. Blessings.
Thank you sir.
Thank you I'm understanding it
thank you for helping us
Nice easy to understand
Thank you sir
we need more
OKAY, GET IT NOW!
awesome easy way to understand. 😁
thank you sir
How did u get 2.607? In standard deviation?
Take the square root of 27.2/4
Thanks
best example
hhhhhhh its funny im waching ma techer and he continues explanetion but am confiused every class i driming ur ma techer anywayes 10q sir
why is n-1 no n?
That's exactly how I learnt it
Perfect
standard deviation how?
THANK YOU SIR 💜
how the heck did you get the 2.607
thank you for this video
I dont understand how to find the squared of any nunber😔
Tysm
Excellent
Thank you so much !!
good work
How to send massege??
At last I.e variance of population, you did some mistake please check once
Thanks a million
thank u so much sir
You are amazing
thank u so much
Thanks sir
Please stop suggesting that students use a calculator to do basic arithmetic like 4+6+8+4+10. I am working with a ten-year-old South Korean student and he could probably teach an American AP Statistics class.
Manak veshlan ye kya hain... vide skp
Tq very much sir
Superb
You lost me on the second part
IT IS SIMPLE THE DIFFERENCE IS FROM THE FORMULA BUT THE ITEMS REMAIN THE SAME. YOU NEED TO SUM THE 27.2/5 NOT(BY 4) MY EMAIL IN CASE YUNUSAABU20GMAIL.COM