mixed model

  1. J

    Tensor notations in multivariate mixed model

    Hi everyone, I have the attached multivariate mixed model in matrix notations. I have been advised to use tensor notations to simplify the model formulation in the multivariate case. Since, I am unfamiliar with the tensor notations, I looked at different online resources but I get lost very...
  2. S

    Non-parametric test with confounding factors (many covariates)

    First, sorry for my English, if I'm not clear enough, tell me! In my project, I have many variables but a very small sample (non-parametric). I'm trying to prove a link between two variables while correcting for covariates. In short, we are looking at white matter tracts and their links to...
  3. S

    0-3 bounded continuous dependent variable

    Hello all, I am working on a difficult (for my abilities) dataset. The dependent variable is continuous [0-3] bounded and was measured between 2000 to 2019 in several locations (not necessarily the same location in each year). So I have a spatial component that would like to account for. My...
  4. M

    p-values histogram for random effects

    I have recently come across with this post: http://varianceexplained.org/statistics/interpreting-pvalue-histogram/ it was great to understand better what my results mean, but I still have a remaining question I can seam to find the answer for. To give you some context, I work with DNA...
  5. V

    Selection of the correct covariance structure – linear mixed model in SPSS

    Hi together, I am currently trying to build a linear mixed model with repeated measurements in SPSS. I would expect that the correlation between my measurements is highest at adjacent time points, so my guess was that AR1 (autoregressive structure) is the right covariance structure in my case...
  6. S

    Mixed model LSMEANS vs ESTIMATE (BLUP)

    Hello, I am analyzing data from a multi-location trial (5 locations) to test the effectiveness of a treatment with 2 levels. The design is RCB with 3-4 replications in every location. I use the model below: proc mixed data=mydata; class location rep trt ; model Y=trt/ddfm=kr2 residual...
  7. L

    Correct p-values multiple testing mixed models

    I am trying to figure out how to correct for multiple testing when having several mixed models. I am using R, nlme package to make the models. I have run 14 mixed models for 14 pre-defined continuous output variables. 1 model is the primary outcome and 13 models are the secondary outcomes. It...
  8. S

    Where can I find resources on statistical modeling of a within-subjects design?

    Hi! I have a mixed model design with 2 within-subjects factors and 1 between-subjects factor. In addition, my dependent variables cover a whole distribution. We tested the distribution from -5 to +5 in steps of 0.5 and would like to model the differences between distributions on different...
  9. T

    Hierarchical linear modeling - minimum number of observations per group?

    I'm looking at the relationship between income and scores on an instrument. Income is estimated by ZIP code. To account for nesting (i.e., people within the same ZIP code sharing an income), I've run a mixed model with ZIP as the random effect. There's a mean of 1.9 observations per ZIP. Is this...
  10. T

    Mixed model regression for income by ZIP

    I'm running a regression analysis to understand the impact of income (predictor variable) on scores on an instrument (dependent variable). The only problem is that I don't know each individual's income; I've estimated it using their ZIP code. I've experimented with a few different methods to...
  11. A

    Mixed model for time trend in R package lme4

    Hello! I would very much appreciate if anyone could help with my model in lme4. I have a dataset with 100 persons, specified by ID. Each of them was assessed at three time points, indicated by Time, for a specific measurement, called Score. I want to look at each person's trajectory over...
  12. R

    How to take into account different treatments, doses and starting health

    Hello all, first thread so please be kind! I have rudimentary statistics knowledge of anovas and regression but am piling through how-to videos of GLMs to no particular avail regarding the comparisons I want to make. I am analysing a simple bioassay experiment with nematodes, whereby I exposed...
  13. A

    Mixed Models: challenge to solve

    Hello there! I have a question concerning my data and the use of Mixed models in SPSS 21.0. I want to investigate the influence of the independent variable 'altitude' (coded 1 to 5) on the dependent variable 'time' (numeric) of a certain test. This test is conducted in 16 individuals and...
  14. S

    meta-analysis vs. random effect combined analysis

    I have data from 200 similar studies, all measuring the same effect of a continuous independent variable on the same continuous response. I say similar because the designs are different (split plot vs. rcbd) and the levels of the independent variable is not the same across all studies. I have...
  15. T

    Help in analyse display

    Hi. I used R to preform "logistic mixed-mode", and now i struggling in how to present it in a table. Maybe someone has an example that i can count on? thanks
  16. S

    How to analyze repeated measures game data with changing difficulty levels?

    Participants: 19 children participated in the study. Children were grouped in groups G1 (N=8) and group G2 (N=11) based on their behaviors. A pre-assessment of children behavior in the classroom is done for both the groups G1 and G2 by their teacher in a form of questionnaire. Task: The...
  17. C

    Relationship between quantitative variables in PROC MIXED

    I feel like this is a problem it should not be possible to have, but I'm running analyses using MIXED where the dependent variable and some of the predictors are continuous, while the remaining predictors are categorical, and I can't for the life of me find out how a particular continuous...
  18. C

    Help with mixed model analysis

  19. L

    Contradiction: '‘Estimation of fixed effects’ vs ‘Type III test fixed effects'?

    Hi there, I’m trying to evaluate if there is an effect of a treatment (3 levels) on coffee plants height over 10 different periods of time. Plants are in 9 different blocs, with Blocs nested in Treatment. I’m using a mixed model (under Systat). In the results ‘Estimation of fixed effects’...
  20. S

    Which statistical test to use?

    Hi, I'm struggling with the following; I have two dependent variables (A and B) which are continous and highly correlated with each other (Pearson 0.9). I want to find out if A>B, A=B or A<B. The most logical test would be to perform a paired samples T test in SPSS, but I also want to...