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

    0
    ReputationRep:
    I've determined the best regression equation and have the residual plots of MPG versus CYL, BHP, and WGT
    However, I need to use the residuals from the model to check the assumptions and adequacy of my regression model, and I'm not sure how to do so
    Could anyone please help?Name:  ImageUploadedByStudent Room1459358623.427480.jpg
Views: 29
Size:  220.7 KB
    Offline

    13
    ReputationRep:
    (Original post by Bruce Harrisface)
    I've determined the best regression equation and have the residual plots of MPG versus CYL, BHP, and WGT
    However, I need to use the residuals from the model to check the assumptions and adequacy of my regression model, and I'm not sure how to do so
    Could anyone please help?Name:  ImageUploadedByStudent Room1459358623.427480.jpg
Views: 29
Size:  220.7 KB
    Sure. The plot in the top left is a normal quantile-quantile plot (or qqplot). If the residuals lie along the straight blue line, it is showing you that your residuals are normally distributed - as required. This is confirmed by the plot in the bottom left, which is just a histogram of residuals.

    The plot in the top right is a plot of residuals versus fitted values. Here you are looking for a random equally spread scatter across the graph. Trends would indicate a mis-specification of the functional form required (e.e quadratic versus linear); varying spread across the page would indicate heteroskedasticity. No such problems here.

    The plot in the bottom right appears to be plotting residuals against observation order. This is looking for correlation between residuals, If there was correlation, you'd get runs of residuals on the same side of the zero line (positive correlation) or jumping too-and-fro across the zero line (anti-correlation). I would say there's a faint hint of the latter here; I would do a formal check for serial correlation just to check.
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?
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

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

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