Tagged Questions

3
votes
1answer
93 views

Dummy coding for contrasts: 0,1 vs. 1,-1

I'm seeking your help in understanding the difference between two different contrasts for dichotomous variables. On this page: http://www.psychstat.missouristate.edu/multibook/mlt08.htm under ...
0
votes
0answers
36 views

Multiple Regression questions (restricted regression, dummy variables)

Q1. Model 1: $Y=X_1\beta_1+\varepsilon$ Model 2: $Y=X_1\beta_1+X_2\beta_2+\varepsilon$ (a) Suppose that Model 1 is true. If we estimates OLS estimator $b_1$ for $\beta_1$ in Model 2, what will ...
3
votes
2answers
141 views

Getting rid of a huge categorical factor in multiple regression

I have a large regression problem with a lot of cases, but relatively few independent variables. One of them is a categorical factor with thousands of levels. Robust regression runs forever. In some ...
1
vote
0answers
102 views

Significance testing for different groups in multiple regression with dummy-coded interaction variables

Consider a multiple regression predicting outcome Y using a continuous predictor P and an interaction between ...
0
votes
1answer
102 views

Nominal data multiple regression analysis

I have been given the following data and am supposed to build a multiple regression model to be able to predict the price of a car: Price of Car - SPSS Measurement = Scale Mileage of Car - SPSS ...
1
vote
1answer
565 views

ANOVA or Regression? 1 Continuous factor & 1 Categorical factor with continuous response variables

I have 1 categorical factor (3 treatments) and 1 continuous factor (weight) and then I have 5 continuous response variables. From what I have read, I should not use a two way ANOVA as one of the ...
1
vote
1answer
216 views

Should I use ANCOVA or multiple regression with dummy variables?

I am writing a manuscript using an experimental design which predicts interactions between 1 continuous variable and multiple dichotomous variables, all predicting a continuous variable. As is ...
1
vote
1answer
95 views

Significant regression for the dichotomised predictor variable and not the continuous version of a predictor variable?

I am interested in examining the association between cardiorespiratory fitness and PCA derived dietary pattern scores in 264 adolescents. My cardiorespiratory fitness predictor is vo2max, and my ...
0
votes
2answers
493 views

Categorical predictor variables in multiple regression?

Can I run multiple regression with mostly categorical independent variables? I'd appreciate some examples to cite this approach as one of my reviewers is insisting that I justify the use of multiple ...
2
votes
0answers
98 views

Independent categorical variables and multiple regression with numeric dependent variables

Firstly I am very very new to stats... I am trying to find a relationship between a dependent numeric factor and have 6 nominal, 1 ordinal and 4 numeric independents. I have been using the category ...
4
votes
1answer
260 views

Dealing with a categorical variable that can take multiple levels simultaneously

I recently posted a question with many parts and I'd like to focus in on just one issue that I didn't emphasize in the original post. My data is a list of records, each one representing an ...
1
vote
1answer
214 views

Is it appropriate to do a multiple logistic regression where both the dependent and independent variables are binary?

Is it appropriate to do a multiple logistic regression where both the dependent and independent variables are binary? Or, can I only use simple logistic regression? What's the difference between ...
1
vote
1answer
389 views

Categorical fixed effect w/ 3 levels in LMER

I have a categorical fixed effect with 3 levels that I'm trying to enter into an LME. ...
0
votes
2answers
562 views

Multiple regression with categorical variables

I have a data set with 3 continuous variables and 3 categorical variables. I know that I have to create dummy variables for categorical variables but I am wondering if it is a must to do that for all ...
1
vote
0answers
56 views

Difference between two separate multiple regression analyses and one combined using dummy variables [duplicate]

Possible Duplicate: Should I run separate regressions for every community, or can community simply be a controlling variable in an aggregated model? I have a SPSS model output with fixed ...
6
votes
1answer
377 views

Should I run separate regressions for every community, or can community simply be a controlling variable in an aggregated model?

I am running an OLS model with a continuous asset index variable as the DV. My data is aggregated from three similar communities in close geographic proximity to one another. Despite this, I thought ...
3
votes
1answer
104 views

Does a huge difference in the number of observations in a dummy variable influence its regression result?

I'm currently working on my thesis where I performed a multiple linear regression. The analysis is basically about the impact of projects. Among other independent variables I have the dummy variable ...
3
votes
2answers
2k views

Assessing the effect of adding a variable using stepwise forward logistic regression using Stata?

I'd really appreciate help using Stata to perform a manual stepwise forward logistic regression. I have 37 biologically plausible, statistically significant categorical variables linked to disease ...