1. M

    Assumption for inferential regression

    I was reading about regressional inference and one of the assumptions stated was: The standard deviation of the responses about the population line is the same for all values of the explanatory variable. I understand this as: If X has a certain value the mean value of Y for that X...
  2. R

    Cox regression with age as time scale and the proportional hazards assumption

    Hello. I am currently working on a Cox regression in SPSS (Complex Samples). The cox analysis has age as time scale and calendar year as time-dependent variables, while treatment (y/n) is a factor variable. My problem is that I don't know how to confirm the proportional hazards (PH)...
  3. M

    Assumptions in ANCOVA, and consequences of violating them

    I ran an ANOVA with 4 predictors (2 categorical, 2 continuous) and 1 covariate (continuous). Including the covariate did not significantly alter the main effects of the ANOVA when it was run without the covariate, so I concluded that the covariate did not need to be included in the overall...