# mixed model

1. ### 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...
2. ### 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...
3. ### 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...
4. ### 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...
5. ### 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...
6. ### 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...
7. ### 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...
8. ### 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...
9. ### 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...
10. ### 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...
11. ### 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...
12. ### 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
13. ### 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...
14. ### 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...
15. ### Help with mixed model analysis

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16. ### 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’...
17. ### 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...
18. ### 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...
19. ### 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...
20. ### 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...