+ Reply to Thread
Results 1 to 5 of 5

Thread: How many data points needed before a nonlinear regression model can be performed?

  1. #1
    Points: 1,570, Level: 22
    Level completed: 70%, Points required for next Level: 30

    Posts
    4
    Thanks
    0
    Thanked 0 Times in 0 Posts

    How many data points needed before a nonlinear regression model can be performed?




    With a within-subject design of only one independent variable, I'm wondering how many data points (levels of the indept variable along X axis) do I need before I could attempt to do a nonlinear regression of my data. Each data point would be the average of all subjects' measurements on that level of independent variable.

    Nonlinear regression is preferred because I'd like to characterize the relationship between the dependent and independent variables.

    Any thoughts would be appreciated! I posted a similar question in the stats research forum but didn't get any replies. I thought rewording and posting in the regression forum might help. Sorry for the double-posting!

    Thanks in advance.

  2. #2
    Ninja say what!?!
    Points: 8,297, Level: 61
    Level completed: 49%, Points required for next Level: 153
    Link's Avatar
    Posts
    1,165
    Thanks
    37
    Thanked 84 Times in 76 Posts
    I hope you don't mind me asking. I'm wondering what you mean by "non-linear regression". Would you mind explaining?

  3. #3
    Beep
    Points: 63,217, Level: 100
    Level completed: 0%, Points required for next Level: 0
    Awards:
    Discussion EnderPosting AwardCommunity AwardMaster TaggerFrequent Poster
    Dason's Avatar
    Location
    Ames, IA
    Posts
    11,310
    Thanks
    266
    Thanked 2,202 Times in 1,881 Posts
    Link asks a good question. A lot of times when people think they want to do nonlinear regression it still falls in the realm of a linear model.

    I'm wondering why you're averaging the datapoints though. It's typically better to leave the raw data as is and model the correlations between datapoints inside the model. Sometimes it's alright to average but you don't have to.

  4. #4
    Ninja say what!?!
    Points: 8,297, Level: 61
    Level completed: 49%, Points required for next Level: 153
    Link's Avatar
    Posts
    1,165
    Thanks
    37
    Thanked 84 Times in 76 Posts
    Quote Originally Posted by Dason View Post
    Link asks a good question. A lot of times when people think they want to do nonlinear regression it still falls in the realm of a linear model.

    I'm wondering why you're averaging the datapoints though. It's typically better to leave the raw data as is and model the correlations between datapoints inside the model. Sometimes it's alright to average but you don't have to.

    Hehehe. Right on the spot as usual Dason.

  5. #5
    Points: 1,570, Level: 22
    Level completed: 70%, Points required for next Level: 30

    Posts
    4
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Thanks for your replies.

    I was thinking nonlinear because the hypothesized behaviour for my data would be something that looks like a negative exponential function y=a-b*c^x (or a rational function) that approaches a horizontal asymptote after increasing initially. The premise of the study is hard to explain in a few words, but basically I'm expecting to see some kind of diminishing return after a certain level in X (independent var). It might be a matter of transforming the data first and then looking for a linear regression fit. I am not sure which. Does the choice of linear vs. nonlinear regression affect the data points needed?

    Dason, I was also pondering whether or not I should average the data. After what you said here I am leaning on the side of not averaging the data. Would this solve my problem of too few data points for modeling purpose?

    Thanks for your help!

+ Reply to Thread

           




Similar Threads

  1. Nonlinear Regression for the P/PE of the S&P 500??
    By Turkish721 in forum Regression Analysis
    Replies: 1
    Last Post: 03-20-2011, 04:54 PM
  2. Replies: 0
    Last Post: 03-07-2011, 01:36 PM
  3. Error in parabolic regression of data points
    By strangersface in forum Statistics
    Replies: 11
    Last Post: 11-03-2010, 10:57 PM
  4. Replies: 0
    Last Post: 04-19-2010, 01:14 PM
  5. Binary Logistic Regression with Multiple Data Points
    By newtostats13 in forum Regression Analysis
    Replies: 1
    Last Post: 04-10-2010, 04:26 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts






Advertise on Talk Stats