Linked Questions

16
votes
5answers
11k views

Can I ignore coefficients for non-significant levels of factors in a linear model?

After seeking clarification about linear model coefficients over here I have a follow up question concerning non-signficant (high p value) for coefficients of factor levels. Example: If my linear ...
1
vote
0answers
38 views

How to do regression model selection if dummy variables are involved? [duplicate]

Original post on stackoverflow: https://stackoverflow.com/questions/28773153/how-to-do-regression-model-selection-if-dummy-variables-are-involved I am trying to do a logistic regression analysis in R ...
3
votes
4answers
8k views

Univariate non-significant results becoming significant on multivariate analysis---X-ray waiting times

I'm having a look at x-ray waiting times in an emergency department and how these relate to the day of the week and the time of day that requests are ordered. (Want to know if patients have to wait ...
1
vote
2answers
5k views

What to do with dummy variable that is not significant? [duplicate]

I´m running a binary logistic regression to predict the purchase probability for a product. My model contains mostly dichotomous and categorical variables. One variable, let´s say "decision maker", ...
2
votes
2answers
699 views

What happens if the full model has the smallest AIC?

Suppose I am modelling a binary outcome $y$ with $n$ covariates. If this model has the lowest AIC among all the other ones...would this be the one to use? Also in dealing with categorical variables, ...
2
votes
0answers
747 views

Feature Selection with Categorical Variables: Multicollinearity and Statistical Significance

Building a logistic regression model with three categorical features and one continuous. For simplicity, let's say I have the following features and variables: ...
0
votes
0answers
674 views

Interpreting regression coefficients with a multi-level categorical variable [duplicate]

How do I interpret the coefficients of a Regression with 1 continuous + 1 categorical predictor (with 4 levels - e.g., months) Specifically, is the 1st coefficient equal to that of the 1st month or ...
1
vote
0answers
409 views

How to drop certain values for a factor variable while fitting a GLM? [duplicate]

My response var is a binary variable. In the predictor variable i have a type variable with levels as l1,l2,l3,l4. And when i run a logit (glm(redonse ~ type, family = "binomial"), Some levels of type ...
2
votes
0answers
205 views

Split Factor Levels Or Not In Variable Selection

This question is related to previous ones but I believe distinct. I am primarily interested in prediction and I have access to LASSO variable selection (but without factor level grouping) using the ...
0
votes
0answers
33 views

Dropping dummies from regression by putting them into the reference group [duplicate]

I have the following result of a logistic regression: ...