# Questions tagged [nonlinearity]

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### Closed-form solution of logistic regression [duplicate]

"For logistic regression, there is no longer a closed-form solution, due to the non-linearity of the logistic sigmoid function". Can someone please explain the above quoted sentence in ...
18 views

### If all computed features ( or components ) in Neural Network nodes are positive numbers , does using Relu meaningful?

I am trying to understand the following issue. The reason we use activation functions such as sigmoid,tanh or relu in neural networks is to obtain a nonlinear combination of input features ( x's). My ...
21 views

### Gretl's nonlinearity test

I would like to know the bibliographic reference for gretl's nonlinearity test. Can someone help me? There are two tests for checking nonlinearity in regression models: Lagrange Multiplier test for ...
1 vote
76 views

### Modelling non-linearity for binary independent variables in logistic regression

I have fit a logistic regression where the response variable is binary - whether an interview candidate got the position or not - and the independent variables are a combination of continuous, ...
2k views

### A linear pattern occurs on my residual plot: what can I do?

I'm a bit stuck with a problem here and any kind of help would help a lot :) Just to give a clue about my data. I have 6 independant variables (IV) which are: $X_1$ = Population -within a block- $X_2$...
11 views

### Variable relationship case: x1 is not correlated to y but x2 which is related to x1 is correlated to y

I would like to know what is the specific term given to this case, or how is this justified in technical words: x1 is not correlated to y but x2 which is correlated to x1 is correlated to y.
39 views

### Exploring relation between x and y [duplicate]

While there are numerous methods in exploring relation between x and y upon receiving a new dataset. Yet it seems I can't find any conclusive guide as of the sequence of analysis, e.g. do correlation ...
60 views

### Dataset with low and non-linearly correlated variables: suggestions on modelling strategies

I have a dataset with low and non-linearly correlated variables and I am interested in assessing the relations between the Independent Variable (IV) and Dependent Variable (DV), however I am not able ...
599 views

### Checking linearity in logistic regression

I am conducting logistic regression, and I am a bit confused about the linearity check? I have 18 independent variables, among them, 13 are continuous, and 5 are categorical variables. In this ...
284 views

### How to interpret p values of a non-linear covariate using pspline in a coxph model

I tested the assumptions for Cox proportional hazards model on my time-to-event data. I found that the assumption of linearity between independent variables and model residuals is violated. After some ...
1 vote
89 views

### Does this scatter plot suggest non-linearity?

As part of assumption testing for ordinary least squares (OLS), I am examining the linearity between the variables in my model. I'm using scatterplots between the independent variables (IVs) and ...
1 vote
33 views

### Linear and nonlinear feature extraction methods

I far what i understand, the assumptions for PCA is that data should be linear. What does that imply? let say if i have a data of 1000*100. So all independent variables should be linearly separable ...
870 views

1 vote
51 views

### Left censored dependent variable in SEM

I'm working on a structural equation model in Amos. I have two independent variables, 5 mediators and a left censored dependent variable. The dependent variable is either 0 or a positive amount in ...
122 views

### How do auto-encoders or Restricted Boltzmann Machines find high variance components for non-linear PCA?

I have read about auto-encoders and RBMs being used to perform non-linear PCA by forcing the hidden layers to learn a good representation of the input features with reduced dimensions. But how do ...
1 vote
156 views

### How to balance/interpret increasing "good fit" statistics, but seeing more departing from linear regression assumptions?

I noticed that I can substantially improve my model's R$^2$ and Residual standard error values by adding some interaction terms. My model's statistics go from: ...
1 vote
65 views

### Data transformations in linear model

I'm starting an academic project about transformations in linear models? At the moment I'm listing all the transformations that there are to correct violations on the assumptions of the linear ...
8k views

### How to detect nonlinear relationship?

I have two continuous variables that may have nonlinear relationship. Scatter plot of two variables showed an ellipse shape. Furthermore, both Pearson correlation coefficient and Spearman's rank ...
1 vote