Questions tagged [intercept]

The intercept in regression-type models is the value of the Y variable when all X variables are 0.

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Simulate event rate in logistic regression - Finding the intercept

I want to simulate a logistic regression (using a set of continous and binary confounders with known odds ratios) with a specified probability outcome (e.g. event rate = 0.2). This is actually a ...
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In R there is a problem of intercept and without intercept ,Pearson's Correlation does not follow! Why? (see the bolded resuls)

Xvec <- rnorm(200) Yvec <- 2.6*Xvec + rnorm(200) lmodxy <- lm(Xvec ~ Yvec) lmodyx <- lm(Yvec ~ Xvec) summary(lmodxy) Output ...
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plot probabilities from mixed effect logistic regression with random intercept and fixed continuous and categorical covariate

I have created a mixed-effect logistic regression model with a random intercept, a ...
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Formula for type III sum of squares of the intercept term in linear multiple regression

assume we have the regression model: $$Y = b_0 + b_1 x_1 + \dots + b_k x_k + \varepsilon $$ I know the formulas for all type III sum of squares for the regression terms except the formula for SS of ...
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Is it valid to solve an equation for multiple coefficients, then average them to obtain overall effect?

I have a regression model, the setup for which is as follows: I am using manyglm, a multivariate general linear model approach to determine the difference in several invertebrate species between two ...
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Can I average out a constant (intercept) in OLS regression?

I have a OLS regression in the form: $$Y_t=\alpha +\beta X_{t-1}+\varepsilon_{t}$$ Can I average out the constant during the OLS estimation/derivation and report, $$y_t=\beta X_{t-1}+\varepsilon_{...
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Is it necessary to include all levels as random intercepts in a multilevel model when they are perfectly nested?

I am running a mixed-effects model in R and I want to have random intercepts for two sampling levels, country and site. The ...
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Are HAC robust standard errors robust against autoregressive conditional heteroskedasticity?

Suppose I have a GARCH(p,q) model with constant conditional mean, \begin{aligned} y_t &= \mu + u_t, \\ u_t &= \sigma_t \varepsilon_t, \\ \sigma_t^2 &= \omega + \alpha_1 u_{t-1}^2 + \dotsc +...
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Deming regression implementation: force intercept to 0

I implemented Deming Regression in a known programming language, using the algorithm from here: https://en.wikipedia.org/wiki/Deming_regression However, the algo does not specify what to do in case we ...
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Why is PCA "a regressional model without intercept"?

As stated in How does centering the data get rid of the intercept in regression and PCA?, PCA is a regressional model without intercept. Thus, principal components inevitably come through the ...
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Should the intercept be included when you check the condition index?

Many sources state that a condition index >30 constitutes a multicollinearity problem. When I've tried to implement this check in practice, I've realized that the condition index (and VIFs) change ...
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Is the intercept estimation affected by multicollinearity?

Suppose I am running a regression $$x_t = \alpha + b_1y_{1t} + \dots + b_m y_{mt} + \varepsilon_t$$ where the $y_{i}$ are potentially linearly correlated (Some have an IVF bigger than 4; generally ...
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Extreme estimated coefficients

Below is a part of my summary(lmfit). It shows a very extreme intercept. I can successfully calculate some fitted values based on the coefficients. However as ...
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What is the role of an intercept in testing the linear hypothesis b1 = -b2?

EDIT2: Possibly the short version of the question is just how would I test cat2 = cat3 in the STATA example in the link below I would like to test the hypothesis that $\beta_{typeprof} = -\beta_{...
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Is it possible to center orthogonal polynomials in multiple regression

I have a regression model that looks like the one below. $$ Y = \beta_0 + \beta_1T + \beta_2T^2 + \beta_3T^3 + \beta_4D + \beta_5D*T + \beta_6D*T^2 + \beta_7D*T^3 $$ Where ...
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All variables are not significant, but intercept is

I am using SPSS for the first time and just trying to make sense of my findings. I had two IV (nationality, age group), each with 2 levels (English-non English; young-old), which is why I ran a 2x2 ...
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ICC in Random intercept model with a predictor variable

Are we able/ or is it correct to calculate ICC in random intercept model which has a preditor variable within? Does this value give us the variation of the outcome which is purely related to subject ...
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Poisson Regression with both categorical and numerical variables: interpreting the outcomes and intercept

I have some difficulties in thoroughly interpreting all the outcomes of the Poisson Regression Model. I have a Poisson regression model with Observed deaths as dependent variable, A categorical ...
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When you are running an analysis with only an intercept, does it make sense to include random subject and item intercepts?

Lets image a study where people get two shapes and are told to pick one. They each get 40 trials, each with a different shape/colour. There are 40 different pairs of shapes. There are 100 participants....
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How to decide if I should fit SARIMAx with or without intercept

I am trying to find the best SARIMAX model for my data, I am using auto_arima to find the order(ARMA and Seasonal) of the model. How do I decide whether or not I ...
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VAR-model include constant or not?

I am estimating a var model with four variables: GDP, investemnt, inflation and unemployment. (all in growth rates). Now I estimated it once with a constant and one without. The model is not changing ...
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Components of the intercept within regression and colon interaction (:)

I'm trying to figure out which elements are part of the intercept within a regression model characterized by colon interaction (:). This is the model: Y ~ A*B + A:B:C The independent variables are: <...
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Understanding the intercept in an unadjusted logistic regression

I have performed an unadjusted logistic regression using weights (obtained via genetic matching) as below. I am using the survey package to make working with the ...
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Why are the intercept values of my QR non-monotonic?

I was led to believe that when conducting quantile regression you would expect intercept values to increase as you go up quantiles. However, I have run a quantile regression and the intercepts are as ...
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Is the random slope for a binary, categorical variable in a mixed model also reported in reference to one of the categories?

I'm wondering if I should be interpreting an estimated random slope for a binary categorical variable in the same way that I should be interpreting it if it were a fixed effect. That is, is it ...
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Interaction term btw. binary and continuous variable - dropping the intercept?

I run a linear regression with many dummy variables (in total 10). Thus to avoid the dummy variable trap, I dropped the intercept and included all dummy variables. Now I'd like to have a look at the <...
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How to interptet Jensen Alpha statistical significance?

When you regress portfolio excess returns against relative benchmark excess return you get a model in which the beta (slope) could be interpreted as the one you get from the CAPM, that is systemic ...
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Comparing fixed intercepts of different mixed models R

Given 3 variables: y is continuous, x is continuous, z is a repeated measures factor, nested within subjects. I have two models from different data sets a and b: fitm1 <- lme(y ~ x + z, random = ~...
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Removing the intercept term for penalized logistic regression

I am working on lasso logistic regression and am trying to remove the intercept term from the penalty function. I have tried to use the mean centering theory but for logistic regression it can not be ...
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Can I recover the level of a dummy in the constant?

In the following country-level panel data equation $$ Y_{it} = c + \lambda_t + X_{it}\beta + e_{it} $$ I use time dummies to capture the year-fixed effects, $\lambda_t$. Obviously, one dummy must be ...
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Coefficients in a Randomized Block Design

If, for example, I am running a GLM with Poisson distribution (it could be any distribution) and I have a Randomized Block Design (RBD) [Note: I don't wanna run a GLMM just to put the blocks as a ...
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Permutation test on the intercept in MANLY(1997) framework?

We assume to have the following regression model: $Y=β_0+β_1X_1+β_2X_2+ϵ$ I recall here the Manly procedure (from another post here :How to do permutation test on model coefficients when including an ...
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Hypothesis at 5% significant for slope and intercept coefficient

"Conduct hypotheses tests at a 5% significance level on the intercept and slope coefficient to see if the intercept is significantly different from zero and the slope coefficient is significantly ...
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Minimizing error of intercept estimate for a given N

Suppose you know that $y = a + bx + \epsilon$ is your generating process, where $\epsilon$ is $N(0, \sigma^2)$, but you don't know the parameters $a, b, \sigma$. You have a limited number of trials ...
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Calculate output nodes (consumer acceptance) of neutal network

To make it a bit easier I am using round numbers (integers) in this example. We have to calculate the value for consumer acceptance. Therefore we have the following input variables (fat = 3; salt = 2)...
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How to determine bias in simple neural network

I have built a very simple feed-forward neural network which given an input $x \in \{0, 1\}$, it is trained to learn $f(x) = x$, the identity function. Below is a model where on iteration $i$, $x_i$ ...
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Negative and not significant intercept in multilevel model

the objective of my work is to estimate whether policies can increase men's time investment in housework. In order to estimate whether the regulation of normal weekly working hours affects men's time ...
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Estimating intercept term in simulation study

I am working on a simulation study in which I have generated data to mimic a scenario with treated and untreated members of a population along with a number of baseline covariates. I am using those ...
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126 views

How to Interprete Constant Intercept in Log Models?

Even though this seems like an especially simple question, I am not 100% sure about what the constant in a log-log model, log-level, or level-log model means. For example, in log(weight) = 8.29 - 0....
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Unusually high intercept for one of the data sets

I’m running a regression to test the stock market in Sweden. In essence, I have made a categorization of two types of buys and two types of Sells. Then I have divided the sample containing all trades ...
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Should an ARMA model always include a constant term?

Should an ARMA model always include a constant term? And if not, when is it appropriate to drop the constant?
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Example for Time Series with Drift and one with Trend

after going through a few posts here on CrossValidated, StackOverflow and Google, I am still puzzled how I can detect whether a time series has a "drift" and how it differs from trend. Here are four ...
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When nature passes through (0;0): what are the consequences for a linear mixed model?

I'm analyzing the data for my master thesis; it's about photosynthetic efficiency for 10 different genotypes of a certain plant species (genotype=Accession in my dataset). For each Accession, I've ...
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GLM - compare the estimated model with the model with intercept-only

I have this glm output. How do the test to compare the estimated model with the model with intercept-only ? How can I comment on the result ?
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How to obtain OLS estimators of the slopes using the deviations from their means

In my econometric course we were given the exercise to show that the OLS estimators of the slopes can be derived by converting the data to deviations from their means. Furthermore, I'm also supposed ...
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Power calculation to test different intercepts in simple linear regression

I have two groups of data: patients and healthy controls. I perform a measurement and a modelled estimation of this measurement on both groups. I then calculate using simple linear regression ($y = b\...
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How to adjust lm Estimates and SE relative to the Intercept

I have a question regarding the output from lm in this table below: ...
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Slope testing for regression lines between non-normal explanatory and response variables

I would like to estimate a regression line between my explanatory and response variables. The explanatory and the response variables are (paired) instrumental measures of the same thing under ...
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651 views

The Intercept terms for Ridge regression, lasso , pcr and PLS (elements of statistical learning)

In table 3.3 (page 63) of the elements of statistical learning book, the intercept terms for Ridge regression, lasso , pcr and PLS differ. However, according to the theory in the book, these models ...
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Interpretation of coefficient sign change and order of terms

I have a logistic regression with data that are kind of like this: ...
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