Measures of Location & Spread 11 • Variance and Standard Deviation • Stats1 Ex2E • 🤖
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- เผยแพร่เมื่อ 16 ก.พ. 2021
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![A-Level Maths: L3-11 [Data: Introducing the Variance and Standard Deviation]](http://i.ytimg.com/vi/eZB1TdtO7zQ/mqdefault.jpg)
btw for anyone in the comments who is struggling to understand what the veriance formula actually means (like i was) i recommend watching TL Maths vid of it because he has a whole video explaing it from start to finish, helped me a lot understanding it.
Thank you so much! I just watched it; he was so clear and concise!
The MSMSM really came in clutch. The hardest part of this topic for me was forgetting the variance formula. Thank you for this video.
The variance formula is an annoying one! Wish it was more simply like the mean haha. MSMSM was 'stolen' from the legend that is Dr Frost.
Hi, does anyone know how to get the variance on the graphics calculator
It gives you the standard deviation, so you can just square the standard deviation.
great video! may i by any chance know your name sir?
👋🏼 I’m Seb Bicen!
Hi, would they ever ask you to not use your calculator for any of these questions? Like they specifically tell you to use the formula and show ALL your working. Thanks
No, I have never seen this before - it's always been in tabulated form of from summary stats.
do we have to know how to calculate the standard deviation from a frequency polygon without a calculator?
No, I think it'd be something we could use just using the stats function on the calc.
I don’t really understand 21:36 and the idea of the standard deviation being affected. I was wondering if you could explain?
Data points that are added inside one standard deviation either side of the mean make the data for condensed on the whole, and so reduce the standard deviation (as this measures how spread out data is). If it’s outside this gap, you’re adding a value that will actually make the standard deviation bigger. If you add a value to the data set exactly one standard deviation above the below the mean, it shouldn’t affect the standard deviation at all. You can investigate this by looking at the formula for standard deviation!
His Sir, May I ask what calculator do you recommend and where is the best place to buy it from.
Thanks for your precious help.
The ones that are used most in A-Level Maths are these: www.casio.co.uk/calculators/a-level
You can just search online for where you can find the best price for them! :)
@@BicenMaths thanks 🙏
I thought you were given the formula for your exams
surely you don’t have to remember the formula as the standard deviation formula is in the formula book ?
No, you don’t have to, but I advise my students to - looking in the formula book can waste precious time with many students running out of time in the exam. My advice is to memorise it whilst practising questions!
i guess this is where statistics gets a lil more complicated lmfao
Yes, it does 😆
Hello Mr Bicen. Just a Quick one. I'm really struggling with a question from the text book. 5b form Exercise 2E has got me stumped and i can't find any information about how to carry out this calculation. I'm guessing it is reasonably straight forward and I am missing something but I can't work it out. How to calculate how many students receive pocket money more than ones S.D. above the mean. The figure above the mean is £11.57 which falls within data set 11.50
I think they are actually asking for an estimate, so I’d use linear interpolation to estimate how many in that group are greater than 11.57. Let me know if that is enough help!
@@BicenMaths Hi. Yes thank you for your help on this. I see it now. I think i was over complicating it. Have a good summer holiday. Thanks, Rob
17:36 So for standard deviation or variance questions involving grouped data we always take a midpoint ?
Yes!
hello sir, is the formula for variance in the formula book given in the exam
nope
Not directly, no - it's elsewhere in the formula book in different forms. So have a look through and see what I mean...
@@BicenMathsthe standard deviation is in it though? so just square whatever you get for that?
Hi Mr. Bicen, for 20:10 I just wanted to double check that writing it like that in the exam and using our calculator would gain full marks? Thank you!
Yes! :)
thanks byson