polynomial regression

  1. E

    Linear modelling

    Hi, I need some help with a modeling query: I have fit 100,000 linear models: M ~ age + age^2, M is the frequency. I found 2,000 models were significant, but would like to narrow it down to find the most ‘extreme’ cases. Is this possible? Does anyone have any suggestions or any references...
  2. M

    Polynomial regression interpretation

    I am running a logistic regression to find how font manipulation (x1) and people perceptions over how easy it is to process the information (x2) influence the online buying behaviour (y). I was especially interest to see if x2 acts like a moderator. Initially I have got to the following...
  3. R

    Interpreting the R Polynomial Regression output

    0 down vote favorite I have the following linear regression output with two quadratic terms and I am unsure how you make the general equation from this for predicting values for Y outside of R software. Any suggestions are greatly appreciated. e.g...
  4. S

    Error with "lowess" function in R

    I have a problem with lowess function to smooth time series NDVI (8-day image from apr to oct in Julian day) as a function of time by polynomial regression in R. Here is the scripts I run: #Create a time vector to act as x time<-sort(sample(97:297, nlayers(ndvi2000crop1)))...
  5. C

    fiting a model to data with two peaks (bimodal?)

    I have plant growth data dependent on temperature on a yearly basis for 6 years. The data exhibit two 'peaks' in growth during the season, with a dip in between. Individually, the yearly data does not appear to be normal using a probability plot. But when the data is collapsed into one column...
  6. J

    Overcoming small dataset anomalies in genetic algorithm

    Hello Talk Stats, this is my first post on this forum, interestingly typing in modeling forum in google took me to a series of websites that was not my desired search result. So I am currently making my 6th version of a model designed to predict the likelihood of of a particular medical...
  7. A

    Interpretaing the coefficients of polynomial regression and multiple regression.

    How do i interpret the coefficients of the 2nd degree polynomial regression model: (crop yield)=1.22+2.1(Nitrogen doses)+3.1(Nitrogen doses)^2 under multiple regression model: (crop yield)=1.22+2.1(rainfall)+3.1(modern tech) Don't think this is a homework.I want the exact interpretation of...
  8. C

    comparing regression coefficients between different models to see if they are similar

    Hi all; This is a very elementary problem; but unfortunately, my strengths do not like in statistics: I am trying to describe plant growth over time using accumulated temperature (dd) as my independent variable and the plants 'growth stage' (gs) as my dependent variable. The shape of the...
  9. C

    Not Quite Quadratic Regression

    Hello all, I predict an u-shaped relation between two variables, y and x. If I perform a quadratic linear regression, i.e. use a model like y = b1 + b2x + b3x^2 + error, then the coefficients b2 and b3 are not significant. However, if I change the exponent to something less than 2, e.g...