Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    18
    ReputationRep:
    How do I do standard deviation and mean when only given a large bunch of big numbers? (Please explain in an easy to understand way, this was a question that I completely failed in my test)
    Posted on the TSR App. Download from Apple or Google Play
    Offline

    16
    ReputationRep:
    Omg I'm doing Statistics.


    I'm just learning myself but standard deviation is the amount between each score or value.

    Standard dev is the square root of the variance. You have to do variance 1st.

    I don't know how you got to standard deviation and don't know how to do mean. But mean is the average. Look up how to do average, then do variance. Then tap square root on your calculator...
    Offline

    11
    ReputationRep:
    Hi, Given a large bunch of numbers you will need to calculate the mean. That is all the numbers added together divided by the amount of numbers there are. so if u have 78 numbers for example, your mean would be all the numbers added together divided by 78.

    Standard deviation is best described with an example. Say we have the numbers:

    2 4 5 6 8 9 10 and 12 to find the variance is the mean of the squares, minus the squares of the mean.

    The mean is (2+4+5+6+8+9+10+12)/8 = 7 squaring this is 49. This is the square of the mean

    the squares of 2 4 5 6 8 9 10 and 12 would be 4 16 25 36 64 81 100 and 144. thats eight numbers so the mean of this set of numbers is (4+16+25+36+64+81+100+144)/8= 58.75 So the mean of the squares is 58.75

    SO the mean of the squares minus the square of the mean is 58.75 - 49 = 9.75 this is the variance

    The standard deviation is just the square root of this which is 3.12 (2dp)

    (Disclaimer. If you are doing further maths there will be a slightly different method if you are sampling)
    • Thread Starter
    Offline

    18
    ReputationRep:
    (Original post by TheEngineer12345)
    Hi, Given a large bunch of numbers you will need to calculate the mean. That is all the numbers added together divided by the amount of numbers there are. so if u have 78 numbers for example, your mean would be all the numbers added together divided by 78.

    Standard deviation is best described with an example. Say we have the numbers:

    2 4 5 6 8 9 10 and 12 to find the variance is the mean of the squares, minus the squares of the mean.

    The mean is (2+4+5+6+8+9+10+12)/8 = 7 squaring this is 49. This is the square of the mean

    the squares of 2 4 5 6 8 9 10 and 12 would be 4 16 25 36 64 81 100 and 144. thats eight numbers so the mean of this set of numbers is (4+16+25+36+64+81+100+144)/8= 58.75 So the mean of the squares is 58.75

    SO the mean of the squares minus the square of the mean is 58.75 - 49 = 9.75 this is the variance

    The standard deviation is just the square root of this which is 3.12 (2dp)

    (Disclaimer. If you are doing further maths there will be a slightly different method if you are sampling)
    Thanks this is a great explanation
    Posted on the TSR App. Download from Apple or Google Play
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    What newspaper do you read/prefer?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    How to use LaTex

    Writing equations the easy way

    Student revising

    Study habits of A* students

    Top tips from students who have already aced their exams

    Study Planner

    Create your own Study Planner

    Never miss a deadline again

    Polling station sign

    Thinking about a maths degree?

    Chat with other maths applicants

    Can you help? Study help unanswered threads

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.