Standard Deviation_ Help!!

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    Feb 17, 2014 1:36 AM GMT
    I'm having trouble understanding this and how to apply it to real life. Can any brainiacs here explain what this is and how it applies to real life? A real life example would be appreciated.

    Thanks
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    Feb 17, 2014 1:45 AM GMT
    Visualize/look at the curves for the data. The high standard deviation data is flatter.

    400px-Comparison_standard_deviations.svg

    http://en.wikipedia.org/wiki/Standard_deviation
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    Feb 17, 2014 1:50 AM GMT
    Simply, if you look at the construct intelligence (IQ), most people would fall in the average range, this would be the mean. There would be a low average and a high average so this would be one standard deviation away from the mean. Look at it as variations from the mean. At the extreme ends, there is giftedness and intellectual disability.

    Hope I didn't confuse you, I'm no good at explaining.

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    Feb 17, 2014 1:51 AM GMT
    Standard deviation: Liking the same sex.
    Non-standard deviation: Liking farm animals.
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    Feb 17, 2014 1:52 AM GMT
    Jaggal saidA higher standard deviation means the values are much more distant to from each other.
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    Feb 17, 2014 1:59 AM GMT
    Jaggal said
    Lumpyoatmeal said
    Jaggal saidA higher standard deviation means the values are much more distant to from each other.

    I don't see the difference between both prepositions. I already have enough annoyance between using prepositions in French, English and Arabic, so thankfully in science, you can express with numbers and equations.

    Lol. I can't explain it but it does make a difference, in English at least. English has many subtle rules.
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    Feb 17, 2014 1:59 AM GMT
    Stdev just means how far numbers are from the mean.
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    Feb 17, 2014 2:03 AM GMT
    Jaggal said
    Lumpyoatmeal said
    Jaggal saidA higher standard deviation means the values are much more distant to from each other.

    I don't see the difference between both prepositions. I already have enough annoyance between using prepositions in French, English and Arabic, so thankfully in science, you can express with numbers and equations.

    Here's what I'm thinking; the word "to" generally means going towards something, while "from" means going away. In this context we're thinking of the data with a high standard deviation as having numbers that are spread apart from each other, not spread apart to each other.

    For example, we could talk about the distance of the Earth from the Sun, which implies how far away it is from the Sun; we wouldn't say how far away it is to the Sun.
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    Feb 17, 2014 2:04 AM GMT
    lol We went from Statistics to Grammar. RJ never ceases to amaze me.
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    Feb 17, 2014 2:27 AM GMT
    Jaggal saidI assume you can google how to calculate it etc. but standard deviation simply measures how far apart values are. A higher standard deviation means the values are much more distant to each other.

    Lets say there are 4 people in a class, and this is their corresponding marks on a midterm:

    Lucy: 70%
    Eli: 40%
    Jen: 85%
    Mark: 97%

    Average of the class: 73
    STDEVP (Since we have the whole population here): 21.3

    However, if this was their exam marks:

    Lucy: 70%
    Eli: 70%
    Jen: 70%
    Mark: 70%

    Average of the class: 70
    STDEVP (Since we have the whole population here): 0

    See how the stdev is 0 in the second one because they all got the same marks, while it was much larger in the first because there were differences in the distances of the marks to each other (and the average which was 73%)

    Helps?



    Thanks. I know how to calculate it. What does it mean? What's its real life application? From your example, what is the 21.3 telling me?
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    Feb 17, 2014 5:46 AM GMT
    Can you tell me what the standard deviation of having a 9" cock? I think a lot of us would find it much more interesting. Assuming the mean equals 6.5" and the sample size is 80.

    Hahahaha
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    Feb 17, 2014 10:42 PM GMT
    It's, just like the mean value, a single number description for a large set of data.

    Let's talk about dick size.

    You have to sets of guys (A and B), they have been measured up, and both group have and mean dick size of 6.5 inches, but for group A, the standard deviation is 0.5 inches, and for group B, it's 2 inches.

    It tells you most guys (67% actually) in group A are are between 6 and 7 inches, some bigger, some smaller.

    While in group B, most guys are between 5.5 and 8.5 inches, a few of them even larger or smaller.

    The mean value give you that, just the average, while the standard deviation gives you a idea about the range around the mean value.

    With group A, you play safe, you will likely have a guy not too far from 6.5. With group B, you can have very good or very bad luck ;)


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    Feb 17, 2014 11:07 PM GMT
    ^

    It's actually an excellent explanation. I was going to type something long out but that covers it already.
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    Feb 18, 2014 2:36 AM GMT
    Oh my, someone actually has time to calculate a std deviation for cock size.

    What is the probability of me finding a date on RJ? Hahaha
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    Feb 18, 2014 3:17 AM GMT
    minox saidWith group B, you can have very good or very bad luck ;)

    Which is bad luck, the little one or the big one? 5.5 isn't that small. Or maybe it is in France.
  • jo2hotbod

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    Feb 18, 2014 3:36 AM GMT
    Lumpyoatmeal said
    Jaggal said
    Lumpyoatmeal said
    Jaggal saidA higher standard deviation means the values are much more distant to from each other.

    I don't see the difference between both prepositions. I already have enough annoyance between using prepositions in French, English and Arabic, so thankfully in science, you can express with numbers and equations.

    Here's what I'm thinking; the word "to" generally means going towards something, while "from" means going away. In this context we're thinking of the data with a high standard deviation as having numbers that are spread apart from each other, not spread apart to each other.

    For example, we could talk about the distance of the Earth from the Sun, which implies how far away it is from the Sun; we wouldn't say how far away it is to the Sun.


    So them is it:
    To infinity and beyond

    Or

    From infinity and beyond
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    Feb 18, 2014 3:40 AM GMT
    From infinity and beyond is where the brain sucking aliens came from. To infinity and beyond is where your soul goes when you die.
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    Feb 18, 2014 3:51 AM GMT
    I might add, the larger the sample, typically, you'll have something that goes out of bounds statistically. I.e., if you talk to enough people, you'll find some super crazy ones if the sample is large enough...however...the larger the sample....the more accurate..and reflective the analysis. The larger the sample, the more accurate the stats will become, across the board.

    Stats is a fascinating thing. It's been since 1983 that I took my stats class.

    It'll come together.

    The bigger the sample, typically, the more convergence you'll see.

    Sample as small as 3% can be something like 97% accurate (the confidence) in predictions (don't hold me to this, but, I'm fairly close). That's how election sampling and prediction is done. Having a much larger sample doesn't add a whole lot more accuracy. First thought would be that it does...but, it really doesn't.

    http://en.wikipedia.org/wiki/Sample_size_determinationhttp://en.wikipedia.org/wiki/Sample_size_determination
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    Feb 18, 2014 3:52 AM GMT
    Jaggal saidI assume you can google how to calculate it etc. but standard deviation simply measures how far apart values are. A higher standard deviation means the values are much more distant to each other.

    Lets say there are 4 people in a class, and this is their corresponding marks on a midterm:

    Lucy: 70%
    Eli: 40%
    Jen: 85%
    Mark: 97%

    Average of the class: 73
    STDEVP (Since we have the whole population here): 21.3

    However, if this was their exam marks:

    Lucy: 70%
    Eli: 70%
    Jen: 70%
    Mark: 70%

    Average of the class: 70
    STDEVP (Since we have the whole population here): 0

    See how the stdev is 0 in the second one because they all got the same marks, while it was much larger in the first because there were differences in the distances of the marks to each other (and the average which was 73%)

    Helps?





    Good stuff.
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    Feb 18, 2014 3:53 AM GMT
    minox saidIt's, just like the mean value, a single number description for a large set of data.

    Let's talk about dick size.

    You have to sets of guys (A and B), they have been measured up, and both group have and mean dick size of 6.5 inches, but for group A, the standard deviation is 0.5 inches, and for group B, it's 2 inches.

    It tells you most guys (67% actually) in group A are are between 6 and 7 inches, some bigger, some smaller.

    While in group B, most guys are between 5.5 and 8.5 inches, a few of them even larger or smaller.

    The mean value give you that, just the average, while the standard deviation gives you a idea about the range around the mean value.

    With group A, you play safe, you will likely have a guy not too far from 6.5. With group B, you can have very good or very bad luck ;)




    Ha ha...Gay guys...:-)