Variance and Standard Deviation: Sample and Population Practice Statistics Problems
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- Опубліковано 4 вер 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 UA-cam are primarily for my own college students, so I usually do not have time to respond to UA-cam comments. But, I'll do my best to respond when I can.
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 UA-cam. Thank you for this video, currently taking stats in college.
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.
How hard could've it been for our teacher if he had just explained it this simple?! Thank you so much, man!
Thanks, from South Africa here sir! I have been struggling to know, when to use denominator (n-1) or 'n', you explained so clearer than cristal. Thanks now I have peace of mind, you the bosssss!!
What a brilliant communicator! Totally recommended. Look forward to checking out more of your videos
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!
You just saved my grade. Thank you.
lol funny
Sofia
yh true talk
So where do u school?
You alive?
Thank you soooooo much!! I spent a week trying to understand my online stats class and watched this video 1x and now understand perfectly. YOU'RE AMAZING!!!
ive been having a hard time understanding standard deviation and variance and am more of a hands on person when it comes to learning. Thank you very much this helped A LOT !
I had forgotten this simple procedure and I totally couldn't remember
Credits to you
I think this calculation is correct for population, but here since we have the sample of numbers so the denominator in the formula is supposed to be not n, but n-1 . Thank you for clear explanation.
Wow ! Great explanation.... I am currently taking an online class and read the book and had no idea because the formula was driving me crazy! Thank you!
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
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
My math teacher is not good as u sir simple yet easy to follow and understand each steps of the way.. thank u ...save. A lot of time and brain ...energy. .
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.
sir i really appreciate the way you teaches on this topic, you give more clarity on statistic management concerning variation,thanks
just know that before this I'd used a complicated formula to remember. u saved my time to memorise and understand this thing!!
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 😂😂
This explanation helps me understand very well 🙏🙏. Thank you sir🤝🤝
I know that you made that video since long time, but I just wanted to say thank you for that, thanks a lot;)
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☺️🙏🏻
Thank you i learn something that I didn't know before currently am from gambella region in Ethiopia county of Africa continent
This was very helpful to understand the formulas. He make it seem very simple to do it yourself.
very clear
good teaching
I really needed this lesson before my STAs exam
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..?
Help: 4. Bone density can be measured using a DEXA test. Bone density for a 25-year-old woman is normally-distributed with a mean of 956 g/cm2 and a standard deviation of 5.52 g/cm2. Let X be the bone density of a randomly selected 25-year-old woman in g/cm2.
Selyna Mcgowan hello
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?
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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Thank you so much. This really helped with my stat finals in a day.
It's very helpful, infact when I confuse in my reading (revision) I just visit this clip🙌 🌹🥀💐
i must say thank you and i so glad i came across your video. i really needed this clarification
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
Realy great vedio sir thax for helping
2.3 * 2.3 = 5.29 , round off will be 5.30 , where did you get 5.4 from ?
great video.At least i have understood the difference between population and sample standard deviation
can you please make a video on how to solve problems in statistics and scientific method badly need it for my psychological statistics subject
bro ur a lifesaver.
Hey the formula is different than the one on the internet without negative 1
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 ??
Thank you for this video. Very helpful.
I like your explanation. But I have one problem. Before checking out your video, I had just read a section of a book explaining standard deviation. But in the book's formula, there was no (n-1) it was just (n) and the sigma sign was written in the formula. what is the "1" for and why? It's really confusing
it is an interesting demonstration. you make it easy for us. thanks a lot statistic dojo
Super explanation
Thank you sir
Good explaination.
Thank you so much! This was so helpful! I have an exam tomorrow and was really confused before watching this!
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
Thank you for the help, great example!!
Thank you for your video. It did help me a lot!
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?
super clear explanation
I have a query. why sample std. deviation and population std. deviation formula are differ ? please clear me .
if i think this is easy will i do good in statistics class?
Why n-1 for sample to calculate Standard deviation?
Where did the minus 1 come from? At 3:38 and at 7:06.
what is the standard deviation of the data set 30 0 0 ?
Why is it that when dividing some ppl subtract 1 from it like (n-1) whereas others just divide by n?
This video was so helpful 🙌
I just like this class
thank you so much dear sir
Thank you
please I need assistance for x bar when calculating mean, the symbol is missing in my computer
I LOVE YOUR WORK SIR
Where did you get the 6.8yrs because the square root of 2.607 is not the same.
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.
undestand that, the teahcer has explained the formula.. but how is this related to the initial series??
Thanks so much, really helpful
he is just amazing
Great work ... thank you
thank you so much. it really helps.
Hi sir I would like to ask at 12:49 why 5.4? I calculate here and it shows that 5.29
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
I don't understand how 2.6 is 27.2/4 squared.
simply done. Thank you
is this tony stark?
omg i thought the same thing !!!!!
I think this will help me thanks.
ty for this video, i know how to get the variance and standard deviation
Nice explanation 👍👍
awesome easy way to understand. 😁
thank you sir
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
Where did you get the 2.6?
Plss reply.
27.2÷4=6.8
Then Square Root of 6.8
=2.607....
Thank you kind sir. Blessings.
How we can calculate the percentage of 5 years old could excite in this class?
Thank you so much
thank for your really thinking
Thank you I'm understanding it
I think I just became a stastician
Nice easy to understand
thank you for helping us
i like your classes
very much
pls can u go over it again
Yaaaa good sir and please make more videos on states sir it will help mee sir
Am asking for the interpretation please
This helps me a lot. Thank you very much..
Our professor when he explained about this, he always advise us to search in google. Now I can say he is wrong, use you tube to learn statistics hahahahaha
Thanks that's was really great
Good explanation
hhhhhhh its funny im waching ma techer and he continues explanetion but am confiused every class i driming ur ma techer anywayes 10q sir
thank you for this video