mixed model

  1. C

    Simple Algebraic Calculation about underestimation

    In a findings, it is found that the non-coverage rate for the second-level intercept variance is 8.9%, and the non-coverage rate for the second-level slope variance is 8.8%. Although the coverage is not grotesquely wrong, the 95% confidence interval is clearly too short. The amount of...
  2. J

    Reporting the formula for a mixed model in a paper

    I want to report the basic formula of my mixed model. Everywhere I look for a template the equations seem way too complicated for a journal whose focus is not the stats itself. Before, I had a fixed effects logistic regression model, so I had a paragraph in my paper going something like...
  3. J

    Normal logistic regression vs a mixed model; which to use? benefits gained?

    I have some evidence to suggest that one vaccine was far superior over another and resulted in the local elimination of a disease. Because it affects pharmaceutical companies the information is sensitive so I will share as much as I can. I analysed the following data set using logistic...
  4. M

    [R]: Mixed model for non-normal y with many 0s and some high values in nested design

    Dear all, I am currently writing my master thesis on the effect of a certain insecticide on bumble bee colonies. In particular I am testing whether the insecticide affects virus or bacterium concentrations. In many colonies I haven’t found any viruses, but if they are present they can be in...
  5. B

    Split Plot/Mixed Model Analysis

    Hi, I have a data set that has several variables. I believe it would be most appropriate to do a split plot or mixed model type analysis. It is measuring yield with variables such as plot(these are the replicates), township(location of sub study), year(was conducted over two years thought...
  6. C

    Confidence interval of parameters of mixed-model in R

    Hi , can anyone please explain me the following output produces in `R` when I ran the command `confint(lmer())` . Here is the R code : library(lme4) fm1 <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy) confint(fm1) And the output is : Computing profile confidence...
  7. C

    Example of lmer() function in R documentation .

    How is the following code working ? (fm1 <- lmer(angle ~ recipe * temperature + (1|recipe:replicate), cake, REML= FALSE)) In the formula of lmer : What does 1 before vartical bar , (1|recipe:replicate) , indicate ? How does "recipe:replicate" after vartical bar work ? I...
  8. L

    Multilevel modeling - dependent variable is not normally distributed

    Hello everybody, I am doing the research, using Multilevel linear modeling (MLM), with dependent variable number of days of payment delays, which is not normally distributed. Is that a problem for MLM? Is it necessary for Y to be normally distributed? I have done a winsorisation- have limited...
  9. M

    Mixed model for empty cell design

    Hi everybody, I would like to do a mixed effects regression that is like this: ISI ~ Location + Stage + Stage*Location + 1|Patient/Chan Where Location and Stage are fixed effects, Patient and Chan are random effects and Chan is nested in Patient. Unfortunately I don't have measures...
  10. D

    LMM: what effect does the repeated variable have on the model?

    When making a linear mixed model what does the repeated variable do? I want to be able to relate what I'm clicking on and the statistics that happen. Conceptually, I understand what a repeated measure is, but what is actually happening when I specify a repeated variable in the "Specify Subjects...
  11. C

    software to run ordinal generalized linear mixed model with nonproportional odds?

    Does any body know of a software program that will allow me to run an ordinal generalized linear mixed model with nonproportional odds? I've been trying the mixcat package in R but can't get it to work. Thanks! Cynthia
  12. D

    Confused: Mixed model, step-wise regression, testing for random effects

    Dear all, I want to perform a MLR (mixed model) on a data set (details below) that has both numeric and categorical explanatory variables. The data is as below: Sample number: 85 Response variable: Y (numeric) Explanatory variables: Sr.No. Variable...
  13. B

    Random Sampling in Mixed Models

    Hi, I have a data set that contains 40 firms over 15 years with firm and individual level data, with the individuals being sample randomly from each firm over 15 years. There are time invariant variables at the firm level and the panel design is unbalanced. How should I be looking to treat my...
  14. A

    MLR equivalent for repeated measures, multiple correlated responses

    I'd like to determine the best approach to determining effect sizes for a set of experimental data with multiple correlated responses. Due to repeated measurements and high correlation between responses, I know that a simple multiple linear regression model obviously isn't the answer. The...
  15. J

    Mixed model, repeated measures, manova, nested? nominal

    Hi. I am not sure how to approach the statistical analysis of the following study. Any insights would be greatly appreciated. Thanks! So, I have two independent groups, group A and group B. I am collecting data for 3 different tasks (Task 1, Task 2, Task 3) at 3 different time points, Pre...
  16. P

    Urgent to do Mixed model and Anova in SAS

    I did analysis of effects of 3 different treatments on some variables. 3 treatments -->20 dependent variables I repeated this Experiment 4 times. Now I have a Excel table with all of means I asked to do Mixed Model and Anova. Some places in my excel are empty because I did not get data...
  17. S

    Variance components mixed models trouble

    Hello, I am using mixed models for variance components analysis and have encountered some problems with non-constant variance and non-normal errors. Here is my model (I'm using R): y = 1 + (1|A/B) There are no predictors, just 2 nested factors A and B. Most variables are...
  18. 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...
  19. J

    Correct structuring of random effects?

    Hi I have produced a mixed effects model as follows; lmer(TotalPayoff~Type+Game+PgvnD*Asym+(1|Subject)+(1|Pairing),REML=FALSE,data=table1)- each pairing contains 2 subjects and each Subject is in 2 different pairings with different subjects. Have I structured the random effects in the...
  20. T

    Complex PERMANOVA mixed model nested design in PRIMER

    Hi All, I am trying to use a complex ANOVA design with the Permanova function in PRIMER. I have been working on this for a while with no significant progress, so any ideas or help would be greatly appreciated. The SAS code for my design is: proc mixed data=treatment; class Gap Wood...