interaction term

  1. R

    Interpretation of interaction terms in a multiple linear regression

    I try to improve my statistical knowledge and right now I am working on a regression that contains interaction terms. I am currently investigating the effects of different variables (a1, a2 etc.) on the quantity of chairs sold in a transaction (dependent variable). To see if effects are...
  2. T

    Reporting a significant interaction

    Hi! I am struggling on how to report a significant categorical x continuous interaction, which I found using a negative binomial regression. I have posted the output from STATA below. So far, I have said something along the lines of, "there was a significant lang2 by emotdys3 interaction term...
  3. M

    GAMs: test of simple effects following a significant interaction

    Hello, I am a novice in Generalized Additive Models (GAMs) and I would need some advice on these models. From capture data, I would like to assess the effect of longitudinal changes in proportion of forests on abundance of skunks. To test this, I built this GAM where the dependent variable...
  4. R

    Interpretation of continuous interaction term

    Hi all, I have a question regarding the interpretation of a squared interaction term in the following model: Y=β0+β1X+ β1X^2 + β2Z+ β3 X^2Z X and Z are continuous and X is negatively related to Y whereas Z is positively related to Y. Is it true that a negative interaction...
  5. C

    Hypothesis difficulty

    Let Y_{ij}=1 if the i^{\text{th}} child is classified as obese at the j^{\text{th}} occasion, and Y_{ij}=0 otherwise. The marginal probability of obesity at each occasion follows the logistic model log\frac{\Pr(Y_{ij}=1)}{\Pr(Y_{ij}=0)}=...
  6. C

    categorical variables in regression analysis and interaction terms

    I am learning multiple regression with categorical variables and in a book I came across this problem. For yield of corn suppose there are two factors affecting, nitrogen level and depth of ploughing. Say there are three nitrogen categories(1,2,3) and two depth categories(1,2). There's...
  7. E

    [stata] interaction terms in conditional logit

    Dear all, There is a famous paper by Norton et al. (2003) which describes why stata's wrong about interaction terms in logit regressions. They propose program called inteff that you can download for stata. Maarten Buis also presents a way how to deal with it using odd ratios...
  8. I

    Pairwise Comparisons for Interaction Term, How to?

    Is there any way to perform pairwise comparisons for interaction terms? Linear Mixed Modeling runs pairwise comparisons for simple effects, but not the interaction terms. Thank you in advance!
  9. S

    Plotting Marginal Effects of an Interaction term in STATA 11.0

    Hi guys, I have an interaction term between two variables = xz = x*z and have run the regression xtreg y x z xz i.year y is also a continuous variable 1.4-23.4 x ranges from 0-142 and z ranges from 0-21.8 (not sure if these ranges help) when running the regression my coefficient...
  10. B

    Interaction term in multiple regression with categorical variables

    Hello everybody, I have question concerning categorical variables and multiple regression: My Scenario: I have two independent categorical variables (X1 and X2) coded by dummy variable 0,1, and 2 (i.e. genetic data). If I want to calculate the interaction term, can I also use the product...
  11. R

    Interaction Term Statistically Significant in Full Model, but not Reduced

    As a preface, I had been taught to assess the interaction term prior to higher end analyses. Figuring out whether or not you have to stratify your analysis early on is essential to saving time in the long run. I am in the process of finalizing a manuscript (which has taken about a year to...
  12. H

    Moderated Multiple Regression versus Factorial ANOVA.

    I am analyzing an interaction effect between two continuous independent variables (Z and X) on a continuous dependent variable (Y). I have conducted both, a moderated multiple regression analysis and a two-way ANOVA (spliting each predictor at its median), obtaining different results. Using...
  13. M

    Categorical variables and interaction in MLR

    Would it be correct, to add in multiple linear regrression interaction between two categorical variables (i transformed them - dummy variavles) with coding 0 and 1?
  14. J

    Pointers for a 2x2 Discriminant Analysis? Can you do multiple DAs on the same MANOVA?

    Hi, I was wondering whether anyone could point me in the direction for help on performing a DA on a two-factor (2 IVs each with 2 groups) design. I've got the 2-way MANOVA done and found a significant interaction term, and I was wondering whether there was a better way to handle the data other...