Parameters associated with the particular levels of a covariate are sometimes called the “effects” of the levels. If the levels that are observed represent a random sample from the set of all possible levels we call these effects "random."
-2
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1answer
25 views
A function like lmer?
Can you suggest me any random effect linear model in R? At the moment I am using lmer, but I would like to know if there is any other similar function.
Thank you
0
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1answer
35 views
Simple Mixed Model with 1 Fixed and 1 Random Effect
I have various datasets I need to analyse regarding soil properties, all in the same fashion, with one fixed effect (which is a position along a transect, indicating different land uses). Now my main ...
0
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0answers
21 views
Specifying a correct full model for an unbalanced repeated measures design in R lme4
Recently, I have done a fairly complex experiment, and I am having trouble coming up with a model that is suitable for the data. I have spent a few days reading about, e.g., when random effects should ...
4
votes
1answer
141 views
Fixed vs Random Effects
I have very recently started learning about Generalised Linear Mixed Models and was using R to explore what difference it makes to treat group membership as either fixed or random effect. In ...
0
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1answer
25 views
Specifying multiple (separate) random effects in lme
I was working in R packages nlme and lme4, trying to specify the models with multiple random effects. I found, that only nlme allows to specify the heterogeneous structure of the variance. Therefore, ...
1
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0answers
15 views
Survival analysis in SAS-is there a way to include a random effect with interval censored data?
I'm trying to use some form of survival analysis (e.g. accelerated failure time or proportional hazards) to study seed germination time. My data is interval censored (also called "grouped-time") and ...
4
votes
0answers
44 views
Which model for panel data with dependent variables from [0,1]?
I'm stuck with a regression modeling problem. I have panel data where the dependent variable is a probability. Below is an excerpt from my data. The complete panel covers more countries and years, ...
0
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0answers
35 views
Logistic regression with random and with fixed intercept
I have made logistic regression with fixed intercept and with random intercept on the same data, and the results (the odds-ratios) are very different. Could somebody tell me what can be the reasons of ...
1
vote
1answer
50 views
Random slope in a model without random intercept
I am looking for a model to fit longitudinal data and opted for GLMM with a logit link.
I tried to add random effects but when both a random slope and random intercept are in the model, this does not ...
1
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0answers
18 views
Predicting from the posterior of a random coefficients model
I've got a model that looks like this:
$$Y_{ig} = \left(\beta_{everyone} + \beta_g\right)X_{ig} + Z_{ig}'\gamma + \epsilon_{ig}$$
in R, this is
...
-1
votes
0answers
52 views
What does it mean to model a random effect on a main effect only when testing interaction?
I'm monitoring groups of individuals all composed of one male only and several females. I want to test if var1 is correlated with ...
2
votes
1answer
92 views
Looking for Intuition Regarding Fixed/Random Effect Conundrum
I understand that we use random effects (or mixed effects) models when we believe that some model parameter(s) vary randomly across some grouping factor. I have a desire to fit a model where the ...
0
votes
0answers
26 views
minimum number of data points per group of random effect
I am producing a Mixed effects model with Subject as a random effect. There are 80 Subjects most with 2 data points per subject(some have only one). Is 2 data points per group enough? Is it ok that a ...
2
votes
1answer
123 views
0
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0answers
70 views
Correct structuring of random effects?
I have produced a mixed effects model as follows;
lmer(TotalPayoff~Type+Game+PgvnD*Asym+(1|Subject)+(1|Pairing),REML=FALSE,data=table)-
each pairing contains 2 subjects and each Subject is ...
2
votes
1answer
82 views
Standard Deviation of Random effect is 0?
I have a model with two random effects
> lmer(TotalPayoff~Type+Game+PgvnD*Asym+(1|Subject)+(1|Pairing),REML=FALSE,data=table)-
>m1
each pairing ...
0
votes
0answers
26 views
Question about the relevance of random effects in the big panel-data context
In general, or at least as I know, the "estimation" of random effects does control for the individual/group/... specific variation.
Hence by controlling for this variation by a random intercept- or ...
6
votes
2answers
233 views
How can I test whether a random effect is significant?
I am trying to understand when to use a random effect and when it is unnecessary. Ive been told a rule of thumb is if you have 4 or more groups/individuals which I do (15 individual moose). Some of ...
2
votes
1answer
122 views
Principled ways of constraining $E[Y]=0$ when one of your regressors $\rightarrow$ 0
Consider the following ridiculous example. There is a real, non-ridiculous research question here, I promise -- I'm just a little bit uncomfortable posting what I'm working on on the internet in ...
0
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0answers
57 views
How to perform a MANOVA with a random effect in R?
I performed an experiment where I raised different families coming from two different source populations, where each family was split up into a different treatments. After the experiment I measured ...
0
votes
0answers
43 views
standard error of the mean for clustered data
I have a dataset with clustered data (observations within groups) and would like to make some descriptive plots.
Now, I am a little bit lost on how to present the dispersion of the data (what kind of ...
0
votes
0answers
113 views
Random effect or clustering standard errors in SPSS
I have a sample of 900 events, where an event includes two firms (Firm A and Firm B). I am running a linear regression with one DV (continuous) and 9 IVs (continuous) (including controls). Many of the ...
0
votes
0answers
49 views
Random intercept for different groups of subjects
Is there a way to specify two different random intercept terms for two sub-groups of subjects within a single mixed model? The reason why I'm interested is that it seems that the inter-personal ...
4
votes
1answer
146 views
How bad is considering a random effect as a fixed effect?
In an experiment with 5 technicians from different companies, we investigated effects of new equipments. The interested response variable is categorical.
One thing I am considering is that the ...
0
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0answers
55 views
When using lmer is a random intercept being estimated more than once if specified in seperate grouping factors?
I know there are a slew of lmer specification questions already floating around. Please let me know if this is a duplicate, or if it is deemed off-topic, and I'll delete it.
I am using a forward ...
2
votes
0answers
56 views
How close to zero should the sum of the random effects be in GLMM (with lme4)
I'm using the lme4 package in R to do some logistic mixed-effects modeling.
My understanding was that sum of each random effects should be zero.
When I make toy ...
2
votes
0answers
68 views
random effect or time series model?
I'm modeling longitudinal patient level health records data which will have the following structure:
\begin{equation*}
\text{Prob}(Y_{it}=1 \text{ at time } t \text{ and member } i)=\beta_{i0} ...
2
votes
0answers
76 views
Why is Poisson regression different with glmer and gamlss?
I have a set of count data that seems to fit "Poisson" = not overdispersed, alpha = 0.
The problem is, I get different results using gamlss vs ...
6
votes
3answers
210 views
regression with non-independent data
I will be performing regression on subjects total scores from 2 player games (prisoners dilemma) that they will be playing. I am aware that including both players score from a game will cause problems ...
3
votes
2answers
129 views
Fitted values of a random effect model
I have this model:
$$v_{ij} = 1 - x \beta + \delta_i + e_{ij}$$
where $\delta_i$ is the i-th random effect, $e_{ij}$ is the usual error term. I have obtained the betas and now wish to derive the ...
10
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0answers
178 views
In a multi-level model, what are the practical implications of estimating versus not-estimating random effect correlation parameters?
In a multi-level model, what are the practical and interpretation-related implications of estimating versus not-estimating random effect correlation parameters? The practical reason for asking this ...
2
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1answer
201 views
4
votes
1answer
194 views
When to include a random effect in a model
I'm new to mixed modelling and i'm confused as to whether its appropriate to use a random effect in an analysis I'm doing. Any advice would be appreciated.
my study is testing how well a newly ...
2
votes
1answer
69 views
Reference needed - Who first introduced linear models, fixed and random effects models?
I am writing an essay which briefly discusses linear models as well as models with fixed and random effects. I am googling since ages to find a reference which says who first introduced linear models ...
0
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0answers
71 views
Ordered Probit/Logit with random coefficients
I searched everywhere but I didn't find what I want, that is why I as the question here. Does anybody know of a function in R which allows to estimate ordered ...
1
vote
0answers
105 views
Selecting GAM with/without random effects - residual plots vs. AIC
My question is about fitting GAMs with a random effect in mgcv, using s(x, bs="re"). I understand that determining the random effects structure should occur before determining the fixed effects ...
0
votes
0answers
59 views
covariance estimate is zero for random compoment
My dataset consists of 4 variable: values, dil, exp and sample. There are 170 values obtained for variable values; there are 5 levels for the variable "dil", 10 levels for the variable "exp" and 5 ...
0
votes
1answer
34 views
Missing values in GLMM
I am creating a GLMM based on a experiment where each subject has 2 repeats. In some instances though there is only data for one of a given subjects repeats for most there is data for both. Can I ...
0
votes
1answer
103 views
Trying to compare a fully fixed and and fully random model in R
So I have a data set which I am modeling using the following:
model1 <- lm(subject ~ .^2, data=hre.train)
This model treats all of the variables as fixed. I ...
1
vote
0answers
66 views
Treatment mean comparisons in a mixed model with random and fixed effects
I have run a mixed model with one random effect, one fixed effect and a second order covariate effect. The random effect models the individual experimental units in my study. The LSMeans calculated ...
3
votes
0answers
48 views
Nesting, sort-of: Multiple observations mapping to a single DV measure?
This is a made up example, but it gets to a point I am trying to figure out.
I know that you can use a nested model if your IVs are collected in clusters -- for example, if you want to model the ...
0
votes
1answer
134 views
Binomial GLMM not converging / Random effects variance and stdev = 1 resulting in AIC = Inf
I am using a binomial GLMM to assess differential habitat selection between two species with model selection using AIC.
When I use many variables (8), the models converge but are not significant. ...
0
votes
0answers
114 views
Two way random effect versus fixed effect
I was just wondering whether the usual Hausman test for random effect versus fixed effect in the panel data is also applicable in case of two way random effect vs two way fixed effect.
3
votes
1answer
130 views
Covariance structure for random intercepts and slopes
Can you please help me figuring out what the covariance structure of a model with random intercept and random slope is?
Here is my model $Y_{ij} = \beta_0 + \beta_1 t_{ij} + b_{0,i} + b_{1,i}t_{ij} + ...
2
votes
0answers
131 views
Use of nlme for mixed models of repeated measures with two classifying factors and a covariate
Suppose we have a mixed model for repeated measures with response being $y$ and a covariate being $x$(say, age). There are two classification factors $a$ and $b$. Say, 5 psychological patients($a$) in ...
0
votes
0answers
174 views
Time period Random effect and two way random effect
The stata has the default random effect which is the cross-section random effect. Is there anyway to compute the time period random effect with the same xtreg ...
4
votes
1answer
198 views
Proper bootstrapping technique for clustered data?
I have a question regarding the proper bootstrapping technique to use with data where strong clustering is present.
I've been tasked with evaluating a multivariate mixed effects predictive model on ...
0
votes
0answers
59 views
How to handle messed up block design?
Let's pretend we have got a randomized block design with three blocks. The aim is to study the effect of fertilisation and irrigation on productivity in an apple plantation. Within each block there ...
0
votes
2answers
418 views
Panel regression: what to do when Hausman test fails and want to keep time invariant regressors?
I am running a panel data regression. First, I did a pooled ols regression. Then I did a random effects (re) one. I carried out the Hausman test, and it refuted the null hypothesis (ie. I am ...
0
votes
0answers
92 views
One-way random effects ANOVA model
I'm starting with Bayesian analysis, and I've been trying to understand how to write a model in Bayesian notation that can be translated into what I want to do with my data.
Let's suppose a one-way ...
