Hey! Sign in to get help with your study questionsNew here? Join for free to post

The effect of coding on Sxx/Syy/Sxy?

Announcements Posted on
Take our survey to be in with the chance of winning a £50 Amazon voucher or one of 5 x £10 Amazon vouchers 28-05-2016
  1. Offline

    ReputationRep:
    What is the effect of coding data on the values of Sxx, Sxy and Syy. I realise r just remains the same. This is for statistics S1
  2. Offline

    ReputationRep:
    You're not getting much response - so I'll take a stab at this.

    If you add a fixed amount to either the x or y values you will not affect any of Sxx Sxy or Syy because they all subtract the mean.

    If you multiply the x values by say 2 you will quadruple the Sxx value, double the Sxy value and not change the Syy value.
  3. Offline

    ReputationRep:
    (Original post by ian.slater)
    You're not getting much response - so I'll take a stab at this.

    If you add a fixed amount to either the x or y values you will not affect any of Sxx Sxy or Syy because they all subtract the mean.

    If you multiply the x values by say 2 you will quadruple the Sxx value, double the Sxy value and not change the Syy value.
    So it's like variance then; in saying that Var(2X+5)=22Var(X) in the case of Sxx and then for Sxy it's like standard deviation (presumably because the x value isn't squared in an Sxy calculation).

    Thanks for responding
  4. Offline

    ReputationRep:
    (Original post by the.austrian)
    So it's like variance then; in saying that Var(2X+5)=22Var(X) in the case of Sxx and then for Sxy it's like standard deviation (presumably because the x value isn't squared in an Sxy calculation).

    Thanks for responding
    Yes, exactly the same, make sure you square it as you've said

Reply

Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. Oops, you need to agree to our Ts&Cs to register
  2. Slide to join now Processing…

Updated: May 12, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Today on TSR

Don't be a half-term hermit

How to revise this week and still have a life

Poll
What's your biggest deadly sin?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read here first

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