# Tagged Questions

Use this tag only for regression models (q.v.) in which the response is a nonlinear functions of the *parameters* (not because it's a nonlinear function of the *predictors*).

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### Why is my high degree polynomial regression model suddenly unfit for the data?

I'm building a ridge regression model in scikit-learn and trying to find the optimal degree polynomial to use. The data I'm working with is a fairly predictable time series of hourly traffic volumes, ...
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### How to reduce the number of labels in regression

I'm working in a regression problem, related to bio-signals, where my labels are integer numbers between 0 and 10. I've tried a couple of regression algorithms already, mainly linear regression. Edit:...
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### How to deal with model misspecification - linktest

I am running an OLS model to examine to what degree is the physical quality of life (SF-12 scale) is associated with depression (HADS scale), adjusting by age and the presence of an acute illness (yes/...
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### How to reduce variables in logistic regression?

I am running a logistic regression to predict Yes/No. I have more than 200 independent variables. I have tried to input all the variables, the result is terrible. It is obvious that one variable will ...
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### Confusion about when to use least-squares regression analysis

I am going through an article titled On the misuse of regression in earth science. On page 65, the author say as follows about the least-squares method. It is usual to require that the ...
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### Macroeconomic Variable in Probit Logit Model [closed]

I am estimating a Logit Model in STATA 13. I have an Enterprise data set 2014 collected for 1000 firms. Some of the variables are in continuous form whilst others are binary. I am using Excel to input ...
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### How to decide a model for my logistic regression?

suppose i have a data set containing 9 variables/features (x1 x2 x3 ....x9) and thus resulting into formation of matrix X of dimension (m*9), i have a discrete output matrix(Y) containing binary ...
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### How to estimate the goodness of fit in a non linear regression?

I have made a non linear regression, and when I run an ANOVA these are my results, How can I calculate the R2 or another goodness of fit with these results? Thanks!
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### model for non-linear data with repeated measurements

I have to do a model for non-linear data with repeated measurements. I worked with predatory insects. I did an experiment with 4 treatments, where per each treatment predators received a different ...
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### How does a LOESS model do its prediction?

I understand the theory behind LOESS, but how does it do prediction without coefficients? I'd like to use LOESS prediction, but need to be able to explain it.
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### Nonlinear transformation using the beta distribution

I'm trying to estimate the following equation (abstracted from this paper) in Matlab: $y_i=a+b\frac{(x_i-min(x))^{(c-1)}(max(x)-x_i)^{d-1}}{B(c,d)(max(x)-min(x))^{c+d-1}}+\epsilon_i$ where $B(c,d)$ ...
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### Linear or non-linear model for social interaction with R

The question here is whether the cooperation of people with equal or similar abilities leads to better results than the cooperation of people with different abilities. The setting is a group of ...
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### what makes neural networks a nonlinear classification model?

I'm trying to understand the mathematical meaning of non-linear classification models: I've just read an article talking about neural nets being a non-linear classification model. But I just realize ...
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### weighted stdev or quantiles to show variation

I have data in the "dat" vector and I am looking to report the weighted mean and also some information on the variation of that mean. As a toy example you can see the data in the "value" vector and ...
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### Nonlinear Multiple Regression

I have a dataset that has multiple x predictor values. To fit a model, I was going to use multiple regression but I looked at the scatter plots for each x value and the y dependent variable and they ...
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### suitable non-linear equation to capture a 'J-shaped' relationship between x and y

I am trying to model the relationship between forest age and individual tree mortality rate. The probability of mortality declines rapidly as forests go from being very young, and then creeps back up ...
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### Fitting a nonlinear regression $Y=1 - a^{-bx}$

I have the following dataset: where X:Y 1:0.81 2:0.86 4:0.9 6:0.93 8:0.96 10:0.98 12:0.99 14:0.99 16:1 18:1 20:1 ..:1 Since the limit of the regression ...
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### Validating regression - common and best practice

Is there a reference setting out a best practice way to validate a regression (such as Lasso, but in general any automated regression), and what is done in practice? My motivation for the question is ...
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### How to relate distributions?

I have 100 objects. Each object has 10 (highly correlated) attributes that I can measure. For each object, I obtain 10000 samples of that object's attributes. I now want to relate the attributes ...
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### Why doesn't the logistic regression model include error? [duplicate]

I know it comes from the fact that y is a vector that only has binary values, but I'm looking for a better explanation...
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### What the interpretation when both the non-squared and squared term are significant?

I have a logistic regression model and added for a curvelinear effect both the non squared term and a squared term to the regression model. They are however, both significant. How do i interpret this?
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### Help interpreting interaction terms in proportional cumulative logistic regression- ordinal regression

I am using the polr() function in R to analyze the relationship between a students score on their first exam, their score in their prerequisite course, and their beginning of semester GPA on their ...
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### Which non-parametric multiple-regression methods are computationally efficient with respect to the number of regressors?

I did some regression in R with random forests and got some decent results, $1-\sum{|e_i|}/\sum{|y_i-\bar{y}|}=0.692$, but I want to do better than this. Through my research, I have concluded that the ...
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### How to interpret Quadratic Terms

I'm answering a practice exam questions, and having trouble with one on quadratic terms. Could someone give me a quick summery of 1) why they are sometimes included? 2) How to interpret them? In ...
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### Non-linear function optimisation using nlminb function in R

I have been getting error messages in my attempt to estimate parameters in a non-linear function using nlminb function. The following is the code: ...
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### Can nonlinear regression with least squares estimations be used for testing hypotheses with data containing dependent observations?

I counted the number of animals of a certain species in 6 fixed locations on a monthly basis for 18 months. I now would like to test the effects of location, starting density, and time on the dynamics ...
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### dependent variable in shares, independent variable log transformed

I havea question. My dependent variable is in percentage (shares of renewables in total energy supply). Hence, my variable is bounded but values are not closed to the bounds. My professor told me that ...
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### Nonlinear regression vs. GLMs for estimating ED50

Are binomial GLMs better than nonlinear regression for model-fitting, and predicting ED50s and other effective dose point intercepts? In toxicology it is typical to run an experiment with a ...
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### Significance testing between two hyperbolic curves

I have two curves for biological data (one-site binding). These curves were both fit using the following (Michaelis-Menten) model: BRET2 = (Bmax * RFU_RLU)/(Kd + RFU_RLU) Note: (x,y) here is ...
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### How to assign defined training set, val set and test set for training a Neural net in NNtoolbox?

To find an optimal number of hidden neurons and layers in my code using feedforward net, I use cross validation technique and cvpartition function to split data. Now my aim is to use this split data ...
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### Compare MLR model to model $Y_i = (\beta_0 + \beta_1x_{1i} + \beta_2x_{2i} + \epsilon_i)^{\beta_3}$?

If I have theoretical reasons to suppose the data might be fit with an unusual equation such as the following: $$Y_i = (\beta_0 + \beta_1x_{1i} + \beta_2x_{2i} + \epsilon_i)^{\beta_3}$$ Can I use ...
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### How do you do a non-linear Poisson? What even is it?

I have a count data that I am having trouble transforming to be linear. First, what are smoothing functions and how do I do it in R? Let's use the famous crab satellite example. If you plot width to ...
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### How are the values of knots in MARS calculated?

I'm wondering how the MARS algorithm decides on the specific values for the knots which are included in the hinge functions. Thank you very much.
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### bilinear regression (or broken power law) and non-detections (upper limits)

I am trying to figure out what is the best way to fit a set of two-dimensional data (x and y, presumably independent) with two segments of linear models and a break point''? The tricky part of the ...
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### what do the outputs of usl model mean?

I am trying to understand the summary of the universal scalibility law model: ...
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### One-Step estimators for non-linear regression

'Disclosure': This question is also asked in the economics.stack community, under the tag of Econometrics, with same title. I'm not sure if it's too technical for that community. Let's suppose I ...