# stepwise

1. ### Stepweise step down post hoc test for Kruskal-wallis in SPSS

Hello, What are the criteria for computing the pairwise or the stepwise step-down comparison in SPSS after Kruskal-Wallis? I know that the pairwise comparison is more conservative than the stepwise comparison, but are there any other criteria to decide which post-hoc test to use? Does anybody...
2. ### Stepwise Regression Limitations Explanation

I've recently been working on building a model and have come across a number of different approaches. I'm particularly interested in the limitations of using Stepwise regression as it has a huge amount of criticism online, however I can't find much material detailing why it's a poor method to...
3. ### Comparing 2 similar regression models with and without continuous variables

I have derived a statistical prediction model using backwards stepwise logistic regression in SPSS. There are 5 independent variables which predict mortality, one of which is age (the other 4 are binary variables). I have decided to dichotomise age so that the score can be easily used. I...
4. ### 1)Test multicollinearity b4/after Stepwise Log Regress? 2)Final Equatn 3)Model Select

Hi all, I need to perform logistic regression for my study. Pretty new to it but have read up on it and have tried it on SPSS. I would like to seek the advice from all of you regarding it. A brief description on my study: I want to see which factors (categorical and continuous) are...
5. ### Linear or non-linear regression model

Hi, I have 20 independent variables and 1 dependent. I've used the stepwise method to determined what predictors are more significant compared to other predictors and I ended up with 10 statistically significant predictors. However, I am not sure how check if a nonlinear multiple...
6. ### Multiple Linear Regression Problem

Hi, I want to do a multiple regression analysis. I have one Y which are numeric values (sample number = 85) and the following Xs. Sr No Variable Data type Data example 1 Region 4 factor levels Region ABC 2 Class 3 factor levels...
7. ### Minimal set of new predictor variable(s) and added value to existing predictor

Hi everyone, I am working on gene expression data for 15 genes and am supposed to derive a minimal predictive set of genes that can be used as a marker profile for disease progression. So far, I created Kaplan-Meier curves for all 15 candidates and performed tested for association with bad...
8. ### Multiple regression drops variables

Hi! I am performing a linear multiple regression analysis in spss in 3 steps. In step 1 I entered my control variables (2 interval and 4 dummy variables) using ENTER as the method. In step 2 I entered my 4 dichotomous independent variables, again using ENTER as the method. Finally, in step 3 I...
9. ### stepclass - klaR package. variable selection

Hi all, i am using the stepclass function which is part of klaR package. I have everything running just fine using a stopping criterion based on improvement of the performance measure. However, now i want to run stepclass and stop when the "best" r variables have been found even if the...
10. ### Large Negative AIC with Forward/Backward Selection

Hello Everyone! I am a very new member to the forum, and extremely glad to find this lively discussion environment. I am a post-doc in astronomy, and with not that profound statistical background. I have come up with a bottleneck that like to consult with experts. So, let me introduce my...
11. ### Faster stepwise selection for a large data set?

Hello, I have a large pool of candidates to choose from to perform a stepwise regression. I did some research and found that the R function "step" or "stepAIC" basically uses "add1" and "drop1" to select or drop a variable. This becomes VERY slow when I have more than 50 variables already in...
12. ### Stepwise and Hierarchical regression - can these 2 be combined?

Hi all, I have run both hierarchical and stepwise methods on my data with 34 IVs (categorized under 7 groups of variables), using SPSS. The hierarchical regression allows these 7 groups of variables to be entered in the order that I want, and the SPSS output shows a coefficient table which...
13. ### Forward stepwise regression procedure: application to panel data

I am in the process of evaluating the importance of some factors in predicting stock returns. In this context, I would like to implement the forward stepwise regression methodology. My dataset is comprised of 13,000 securities with monthly data from 1984 to 2012. Since this is my first...
14. ### Manual Forward Selection - order of covariates

Hi all, I have a conceptual model, with different covariates to explain an o=e relationship. I have confounders and effect modifiers. I am unsure, to begin the manual forward selection (for which I will only add variables based on certain criteria), with covariates CLOSER to the main...
15. ### Stepwise Multiple Regression - Case:IV Ratio?

Hi, Having researched stepwise regression there is a clear view that you need to target a Case:IV Ratio of at least 40:1 as "stepwise doesn't generalize very well beyond the sample"... given that I'm looking at running some employee surveys and I suspect the response is going to be very high...
16. ### Stepwise regression in R using multiple variables of choice

Hello all. I need a little help in translating SPSS language into R. In SPSS, you can run stepwise regression by entering them into "Blocks" (which I believe is analogous to steps). Unlike R, which determines which single variables to add or subtract depending on the AIC, SPSS allows to...
17. ### SPSS Output: Increasing "R Square Change" Value

Hello, I have preformed a stepwise regression on my data set using SPSS. In the out put table the "R Square Change" value for the second model is larger than the "R Square Change" value for the first model. I am not sure why that is. I was expecting SPSS to output the model with the...
18. ### Discriminant analysis Eigenvalues

I have a specific question: when running a stepwise Discriminant analysis, if I get 2 or more steps, and then SPSS shows the eigenvalue of "function no. 1" ONLY which explains 100% of the variance, does this mean this function includes the variables in all of the steps? So, for example, I...
19. ### Reduce number of predictor variables ((multi)collinearity): PCA not helpful

Howdy, The attached spreadsheet contains the correlation matrix of predictor variables and response variable. Correlation exists between them. Additionaly included are the results from a Principal Components Analysis on my (scaled) predictor variables. I used the prcomp command in R with the...
20. ### Stepwise Regression

When a variable is added and then removed in stepwise regression, what happens to the proportion of the variance it explained?