Results 1 to 4 of 4

Math Help - Curve fitting when typical regression models fail

  1. #1
    Newbie
    Joined
    Feb 2011
    Posts
    3

    Curve fitting when typical regression models fail

    I tried using a regression model to fit a curve, but none of the typical models work. I'm not smart enough to use other regression methods, but I'm thinking an equation can be derived without it (hopefully).

    The scatter plot shows Average Weight on the y-axis, and a ratio of the quantities of two objects, A and B, on the x-axis.

    I know from work experience the average weight of object A is 33-34 tons, while object B is about 140-143 tons. The purpose of this is to estimate average tonnage by using the ratios of quantity A to quantity B.

    Y-axis = Total Weight (various qtys of A & B combined) divided by the (quantity of A + quantity of B)

    X-axis = quantity of A divided by quantity of B

    Can someone help me with an equation to fit a curve?


    Curve fitting when typical regression models fail-tpob2.jpg
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Mar 2010
    From
    Florida
    Posts
    3,093
    Thanks
    5
    Quote Originally Posted by seligman28 View Post
    I tried using a regression model to fit a curve, but none of the typical models work. I'm not smart enough to use other regression methods, but I'm thinking an equation can be derived without it (hopefully).

    The scatter plot shows Average Weight on the y-axis, and a ratio of the quantities of two objects, A and B, on the x-axis.

    I know from work experience the average weight of object A is 33-34 tons, while object B is about 140-143 tons. The purpose of this is to estimate average tonnage by using the ratios of quantity A to quantity B.

    Y-axis = Total Weight (various qtys of A & B combined) divided by the (quantity of A + quantity of B)

    X-axis = quantity of A divided by quantity of B

    Can someone help me with an equation to fit a curve?


    Click image for larger version. 

Name:	tpob2.jpg 
Views:	40 
Size:	79.8 KB 
ID:	20679
    You could try

    f(x)=\beta e^{-x+\alpha} \ \ \ \alpha,\beta\in\mathbb{R}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,404
    Thanks
    1293
    I don't see why a Least Squares Linear Regression would fail here...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by seligman28 View Post
    I tried using a regression model to fit a curve, but none of the typical models work. I'm not smart enough to use other regression methods, but I'm thinking an equation can be derived without it (hopefully).

    The scatter plot shows Average Weight on the y-axis, and a ratio of the quantities of two objects, A and B, on the x-axis.

    I know from work experience the average weight of object A is 33-34 tons, while object B is about 140-143 tons. The purpose of this is to estimate average tonnage by using the ratios of quantity A to quantity B.

    Y-axis = Total Weight (various qtys of A & B combined) divided by the (quantity of A + quantity of B)

    X-axis = quantity of A divided by quantity of B

    Can someone help me with an equation to fit a curve?


    Click image for larger version. 

Name:	tpob2.jpg 
Views:	40 
Size:	79.8 KB 
ID:	20679
    Is this not the same question (but in disguise) as in your other thread?

    CB
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Regression Models problem =_=
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: June 1st 2010, 05:58 PM
  2. Linear Regression Models (1)
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: May 19th 2009, 05:21 PM
  3. Linear Regression Models (3)
    Posted in the Advanced Statistics Forum
    Replies: 3
    Last Post: May 15th 2009, 07:17 PM
  4. Polynomial Fitting? Regression?
    Posted in the Pre-Calculus Forum
    Replies: 0
    Last Post: March 2nd 2009, 10:59 AM
  5. Help with nonlinear regression / curve fitting
    Posted in the Advanced Statistics Forum
    Replies: 17
    Last Post: June 6th 2007, 10:48 PM

Search Tags


/mathhelpforum @mathhelpforum