mixed effects model

  1. J

    Linear Mixed Effects and interpreting transformations

    Hi, I'm running a hierarchical linear mixed effects model in R (subject is nested in dyad). My dependent variable is a continuous variable. When I run the model I do not meet the assumption of homogeneity. A log transformation on the dependent variable does not work. However, when I use a box...
  2. victorxstc

    Binary mixed-model logistic regression using lmer() of lme4 for multilevel analysis

    In my experiment, each patient has been observed twice, once using placebo and the other time using the real treatment. I want to assess the predictive effects of the treatment and patients' demographics (age, sex, etc.). Therefore I have for example 100 patients, but actually 200 pairs of...
  3. T

    Can an explanatory variable be both a random and fixed effect simultaneously?

    Hello, and thank you for reading. I am trying to test for what environmental variables (3 continuous distance variables e.g. distance from nearest village) influence 1) species richness at the site level (continuous variable) and 2) community composition at the site level (coordinates of...
  4. T

    Nested test to remedy pseudoreplication

    Hello and thanks for taking the time to read this. Data structure: I have two datasets from two protected areas that differ in protection status. Both areas contain 43 and 37 sites each. Question: I would like to know which test would be the best for testing whether the PA status has...
  5. J

    Standard Deviation of Random effect is 0?

    have a model with two random effects lmer(TotalPayoff~Type+Game+PgvnD*Asym+(1|Subject)+(1|Pairing),REML=FALSE,data=table)->m1 each pairing contains 2 subjects and each Subject is in 2 different pairings with different subjects. For some reason the subject random effect has SD =0 I do not...
  6. M

    How to do Regression with many replicates of y at each level of x?

    Hi follows, I have data that looks as follows: X, y1, y2, y3, y4 0, 54.241, 127.728, 127.73802, 127.73802 31, 65.132, 127.729, 127.73787, 127.73792 59, 65.364, 127.729, 127.73782, 127.73789 Where y1-y4 are just independent...
  7. T

    Nested Data - is mixed effects modeling appropriate here?

    Hi! I'm trying to determine the most appropriate way to analyze a data set which comes from a nested experimental design. The basic setup is this: a muscle biopsy is obtained from one of three possible muscles. The tissue properties of each biopsy are tested - the response is "modulus"...
  8. G

    Can you use a mixed effects model if your explanatory variable is count data?

    I'm trying to look at the effect 'density' (count data) has on 'colour' (continuous data), and would like to include 'transect' (categorical) as a random effect. In all the explanations and examples I've found the explanatory variable is categorical - is it simply not acceptable to run a...