# Questions tagged [linearity]

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### Variable selection in ordered ordinal model - transform variables prior?

I am running a series of proportional odds ordinal models. I have a set of predictors that correlate. I aim to find out how effect sizes and significance change after introducing control and ...
• 1
32 views

### Linear regression has good performance in validation set despite not meeting the linearity assumption

I have a dataset with about 8000 samples and 18 predictors (16 continuous, 2 categorical). I am trying fit a linear regression, but despite trying multiple transformations, I can't make it meet the ...
• 33
8 views

### 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 ...
• 101
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### Correlation = 1 with three random variables

Let $A, B, C$ be random variables with covariance $cov(A B) = 0$ and correlation $corr(B, C) = 1$. Is it true that $cov(A C) = 0$?
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### linearity of a measurement device

I like to evaluate the linearity of a measurement system. In order to do so I read ISO 22514-7 as well as Breyfogle's "Implementing six sigma". However, the procedure is still unclear to me. So I'm ...
• 659
84 views

### Why is linearity (as in linearity in BLUE) a desirable property for OLS estimators?

By linearity, I do not mean the linearity of the estimators in the OLS regression equation, what I am trying to ask is why are the beta coefficients a linear function of y(i)'s. Why is linearity a ...
82 views

### Linearity assumption of logistic regression [duplicate]

Do I have to check linearity assumption of logistic regression (Log odds of outcome with continuous variable) using graph of predicted logodds (by logistic regression) and continuous variable Or ...
71 views

### Is there a way to differentiate between linear and non-linear datasets in simulations studies?

I'm trying to find a a measure of "linearity" among different simulated data sets and how I could control for such differences. This idea came from studying Hastie's and Tibshirani's work around ...
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1k views

### Should one drop independent variables if they don't have linear relationship with the response variable?

I am building a linear regression model using Ridge regression. Some of the independent variables don't have linear relationships with the dependent variable. I've tried to do data transformations on ...
163 views

### Linear regression, linearity assumption violated?

Below i have attached a scatter plot showing my dependent variable on the Y-axis and my independent variable on the X-axis I am not sure if the linearity assumption is violated? Can anyone explain ...
• 139
190 views

### SEM 4 questions - testing linearity, sum score, number of variables, independent variables

For my master thesis I'm making a structural equation model. However, I do not have much experience with this. So here are some different questions. I read that one of the assumptions important for ...
246 views

### How to check the linearity of continuous variable in linear mixed model

I'm doing a linear mixed model using lme. In my adjustement factors, I have a continuous varaible (named X1). And I want to check the linearity of this variable using a spline function or a ...
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271 views

### Model assumption of linearity

I am trying to interpret the outcome of a test for assumption of linearity. This is the dataframe: ...
90 views

### Is checking for normality and linearity in this way correct?

Testing normality using a significance test is a little bit useless especially when you have a large sample size So, recently I found a way to test normality by running a fake regression using ...
276 views

### What is relation betwen linearity assumption in OLS and L in BLUE (i.e. OLS is BLUE)

The linearity assumption says that the dependent variable is linear in parameters. When Gauss-Markov assumptions hold, OLS is BLUE, meaning smallest variance amongst Linear Unbiased estimators, where ...
127 views

### How do Component + Residual Plots look like in Polynomial Regression?

Components + resiudal plots or partial residual plots can be used to detect deviations from linearity in multiple linear regression. They work by plotting the variable on the x-axis and the component+...
1 vote
19 views

### linear relationship [closed]

Could the data points fall on the regression line to assume that the relationship is linear, please check the attached photo what if the scatter plot shows that the relationship is linear but the ...
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1 vote
27 views

### Linear Unconditional X-Y, Non-Linear Conditional X-Y

Intuitively, I can imagine that an unconditional (i.e., unadjusted for any covariates) Y~X relation can present as a linear relation, whereas a conditional Y~X|Z relation can present as a non-linear ...
2k views

### Ways of Testing Linearity Assumption in Multiple Regression apart from Residual Plots

I was going through the assumptions of linear regression and of course one of them was linearity between the dependent and the independent variables - to be precise I should say that the assumption is ...
• 136
1 vote
283 views

### ANCOVA - Non-linearity of covariate

I have a dataset where I calculated genetic distances between populations of some animals (a continuous variable). I want to know if these differences are explained by physical or/and ecological ...
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### Cox PH linearity assumption: reading martingal residual plots

According to a lot of ressources about Cox PH model, continuous numeric variables should be tested for linearity assymption by plotting the Martingale residuals. In R, you can use ...
• 1,119
2k views

### Cox PH model: managing continuous variables and linearity assumption

In an epidemiological study, I'm using martingale plot to assess the linearity of continuous variables. Here are the Martingale Residuals (from Null Model) using R's ...
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1 vote
123 views

### Violation of linearity?

Can anyone tell me if, based on this image, the linearity assumption is violated in my model?
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