nonlinear regression

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    Is a bayesian MCMC regression approach suitable/recommended for this complex model?

    Hi everyone. I'm trying to reanalyze the data of an experiment I did using a bayesian approach, but the complexity of the problem has me stuck. I read Richard McElreath's "Statistical Rethinking" (2nd ed.) for useful insight and I think I'm conceptually 80% of the way there, but I could use some...
  2. U

    Linear vs nonlinear regression doubt

    Hello, I am currently working on a study about how much time a chess engine should think per move in a chess game. The inputs (known data) would be how much time is left (in seconds), the evaluation of the engine (centipawns) and the move that is being made. My question is: is it a multiple...
  3. E

    Jacabi Matrix of nonlinear regression model with more rows as observations

    I am wondering why the Jacobi matrix from my model estimated by matlab has three times more rows, as there are observations. I have estimated the nonlinear regression model in the added file by the following command in Matlab: options=optimset('MaxFunEvals', 10000, 'MaxIter', 10000, 'TolFun'...
  4. A

    Least squares estimate of alpha and beta

    My group have different opinions towards the following question: Find the least squares estimate of alpha and beta of the mechanistic growth model: Y=alpha*(1-beta*e^-x) using the following dataset. Y 1 1.1 1.39 1.55 1.63 1.86 1.98 X 0 0.1 0.5 0.8 1 2 4...
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    Can AIC values be combined?

    Hello! I have hunted far and wide on the net in an attempt to answer this. Essentially, I'm trying to combine two AIC scores from different parts of a single data set. I have two models (of the same type: nonlinear least squares fitting a growth curve to population data) that each predict...
  6. C

    Problem with nlme() convergence in a Monte Carlo simulation

    Hello. As part of a Monte Carlo simulation, I'm programming some model comparisons on generated data. The underlying relationship in the data is a two-parameter exponential curve (y=a*e^(bx)), and among the models being compared are hyperbolic (y=a/(1+bx)), and quadratic (y=b*(x-a)^2)...
  7. D

    Linear or non-linear regression model

    Hi, I have 20 independent variables and 1 dependent. I've used the stepwise method to determined what predictors are more significant compared to other predictors and I ended up with 10 statistically significant predictors. However, I am not sure how check if a nonlinear multiple...
  8. F

    problem with defining constraint in Nonlinear Regression

    Hi all I have a question. Is there any way to set a parameter to be greater than the other one as the constraint when we want to use nonlinear regression in SPSS? (in constraint part I just could determine the parameter to be greater than a specific number not another parameter) Thank you
  9. R

    Non-linear modelling with several variables including a categorical variable

    Hello everyone, I am trying to model some data regarding a predator prey interaction experiment (n=26) in R. Predation rate is my response variable and I have 4 explanatory variables: predator density (1,2,3,4 5), predator size, prey density (5,10,15,20,25,30) and prey type (3 categories). I...
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    Having problems with CATREG for big and small data sets and defining scaling level.

    0 down vote favorite I am facing with an interesting problem here. I have a data set containing mixed nature of independent variables (some are nominal, some are ordinal, some are scale). The dependent variable is ordinal. I thought if I use CATREG in SPSS then I am going to get only one...
  11. B

    How to test for and remedy multicollinearity in optimal scaling regression?

    I have a data set containing only categorical variables (both nominal and ordinal in nature). The dependent variable is also ordinal (with 4 categories). I was planning to run a categorical regression with optimal scaling instead of ordinal logistic regression aiming at obtaining a single beta...
  12. B

    R2 values for reduced major axis regression in spss

    Good day! I need to do reduced major axis regression in SPSS, and I am using the Constrained Non-Linear Regression procedure for this (my syntax looks something like this): MODEL PROGRAM A=1 B=1. COMPUTE PRED=A+B*X. COMPUTE LOSS=((Y-PRED)**2)/ABS(B). CNLR Y /LOSS=LOSS. with Y as...
  13. F

    [Error] length of 'dimnames' [2] not equal to array extent

    Hello all, I'm trying to use the user-created multinomRob to make some models for my data. While documentation for that function is great and I think I'm using it correctly, I'm getting the following error when I try to use my dataframes. data <- read.csv("data.csv", header=FALSE) subj1...