All Questions
Tagged with lme4-nlme statistical-power
36 questions
1
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0
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69
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simr Failing to Run, "observed power calculation"
I am analyzing simulated delay-discounting data. The response variable is reaction time in milliseconds. K is the scaling factor describing how much value is affected by delay. College Year is from 1-...
- 11
0
votes
0
answers
78
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How to run a sensitivity power analysis for linear mixed modeling (lme4 and simr)?
We conducted a behavior change field experiment using the following variables:
Two time points (T0, T1)
Two groups (intervention vs. control)
Individual ID (n = 62 in group 1, n = 53 in group 2)
...
- 23
1
vote
2
answers
74
views
Mixed model: Which parameters to provide for sample size calculations?
I am currently planning an analysis in a relatively new area of research and would like to provide data that will allow for future power analyses. Unfortunately, I am completely lost in the ...
- 433
0
votes
0
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112
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Simulating Power Analysis for Mixed Models (lme4 and simr)
I would like to calculate an a-priori power analysis for a within-groups study with the following design:
participant_id
condition (within groups - A, B)
covariate (scale 1-7)
questionnaire items (...
- 133
0
votes
0
answers
26
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Regression model detects effects that are much smaller than it was powered to detect
I have a mixed-effects regression model with n=250 in each condition. My power analysis predicted that the model would be able to detect effects larger than Cohen's D = 0.20. However, the model ...
- 413
4
votes
2
answers
197
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What is the optimal method for distinguishing lack of power from non-significance in linear mixed models?
I have a linear mixed model and am interested in the significance of the fixed effects.
I run run 2 identical models, except the second eliminates data points that are outliers (i.e., a sensitivity ...
- 542
1
vote
1
answer
30
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How can I interpret non-significance in models built with subsetted data?
I am working on revisions, and it was requested that I re-run my models separately for males and females. When I do this, I lose statistical significance in some tests in females but not in males, but ...
- 237
1
vote
1
answer
299
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How to determine sample size needed for sufficient power to compare between levels of a fixed effect in a mixed model?
I ran a pilot study for a within-subjects experiment where the fixed effect of interest is categorical, with 4 levels. The research question involves comparing which levels of this IV can ...
- 11
3
votes
1
answer
1k
views
Calculating minimum sample size required for repeated measures linear mixed model using the simr package
I would like to use the simr package to calculate the smallest sample size needed to achieve $0.80$ power at the $0.05$ alpha level while accounting for a small ...
- 31
2
votes
1
answer
542
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Power analysis for simple LMER model in R from scratch
I'd like to compute power for some rather simple lmer models. I am aware of some packages like simr but the tutorials are not easy to follow because they ...
0
votes
0
answers
74
views
power analysis for glmer mixed models
I want to know an appropriate way to conduct a post-hoc power analysis for several glmer models built in R using the lme4 package. A reviewer asked for this.
What I did:
I used the R package simr ...
- 23
0
votes
0
answers
74
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How to simulate monotonic data with constrained range?
I'm running simulations for a power analysis for a negative binomial GLMM. The dependent variable has a negative binomial distribution and will be measured at five time points. It has two other ...
- 202
2
votes
1
answer
251
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Choosing experimental design and sample size based on power analysis for mixed models using pilot data
I used simr package in R to determine the minimum number of subjects I need to obtain the main effect of variable A and the interaction between variable A and B on ...
- 373
1
vote
0
answers
161
views
How to test the power of standardized coefficient in simr?
I often need to conduct power and sample size calculations for
multilevel regression, typically for a fixed effect. I use the simr
package which works great, but I can't figure out how to test the
...
- 2,825
1
vote
1
answer
83
views
Power calculation by simulation - what do I do with model failures?
I'm trying to run a power calculation by simulation on a set of exponential decay datasets using the nlme package in R. Here's the process:
Simulate a bunch of exponentials, using some conservative ...
- 143
1
vote
1
answer
837
views
Why is simr constantly giving me erroneous power results in R? [closed]
No matter what model I fit in lmer, it seems like simr never gives an accurate read of what the data is doing. For example, the ...
- 18.5k
3
votes
1
answer
1k
views
Post hoc power analysis for multilevel regression analysis
I have a multilevel model with 2 levels (L1 = individuals, at least 710 per country; L2 = countries, 17 total)
...
- 1,782
1
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1
answer
524
views
1
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0
answers
122
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Is there a function to calculate Sample Size for random intercept model in R
I am new to random effects and am trying to understand sample size/power/ effect size calculations.
Let's say I have a dataset with 52 subjects who reported anxiety outcomes at four points in time. So ...
- 11
1
vote
1
answer
2k
views
Sample size calculation for linear mixed-effect models without data
I would like to know how to do a sample size calculation without data/simulation for mixed-effect models.
To briefly explain my research, I want to investigate which method (A or B) is more effective ...
- 11
1
vote
0
answers
754
views
How to interpret effect sizes in simr power simulation for mixed models?
I am conducting a power analysis for linear mixed models. I want to know what sample size is needed to find a specific effect size for an interaction. I am testing the interaction effect by comparing ...
- 113
0
votes
0
answers
118
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Adjust alpha in post-hoc-power when bonferroni corrected before?
I was wondering whether I need to adjust my alpha when testing the power of effects for which I have adjusted for multiple testing.
This is what I did:
Tested the effects of 8 (generalized) linear ...
- 433
0
votes
0
answers
1k
views
I am trying to use the simr R package to do an (observed) power analysis for a glmer model
EDIT: Pardon me, I am double-checking things. Some of these numbers may be totally incorrect.
This is unexplored territory for me, so I was hoping that somebody could confirm that I am doing this ...
4
votes
1
answer
409
views
Should I remove a significant covariate from my mixed-effects model because it's underpowered?
I tried figuring out the answer by reading the comments in this thread but I am still confused. Should I remove a covariate from analysis when it comes as significant but power simulations finds that ...
- 199
2
votes
0
answers
1k
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minimal detectable effect size in linear mixed model
I'm trying to find the minimum detectable effect size (MDES) given my sample, alpha (.05), and desired power (90%) in a linear mixed model setting. I'm using the ...
- 103
3
votes
0
answers
4k
views
Power-analysis and effect size in linear mixed models (post-hoc)
I'm currently analyzing data using linear mixed models (lme4 package in R) for my master thesis, and my promotor suggested running a post-hoc power analysis to justify that some factors did not end up ...
- 31
0
votes
1
answer
42
views
Factors affecting SE and power in lmer: how do I have lower SD&CV but higher SE and lower power?
I using simulated data sets to compare the ability to two different experimental designs (A and B) to detect a interaction between two variables (x and y) in determining the observed output (o). The ...
- 131
1
vote
1
answer
1k
views
Can I use "simr" package for power analyses on ANOVA models? [closed]
simr is an R package for conducting power analyses on linear mixed effects models. One might compute power for a model with:
...
- 127
6
votes
2
answers
9k
views
Why this simple mixed model fail to converge?
I have data on which I would like to compare the mean of the value variable
between day 28 and day 83. Because the experience involve pseudo-replication
(...
1
vote
0
answers
1k
views
Power and Sample Size Estimation for Logistic Regression (Mixed) Models
I am working on designing a study based on some initial pilot data and would like to conduct a sample size estimation. I have previously used simr with linear mixed ...
- 163
0
votes
0
answers
675
views
Power analysis in a mixed model with a within-between subjects interaction
I have data from an experiment in which each subject was assigned to one of 4 experimental conditions (CONDITION, a between-subject factor), and then faced 4 similar but distinct tasks (TASK, a within-...
- 107
3
votes
2
answers
440
views
How to change variance-covariance matrix in mixed models?
I'm currently trying to do power calculation using SIMR package in R.
To start off, I first created the following model which defines my study design with simulated output y:
...
- 51
0
votes
0
answers
2k
views
GLMM with highly unbalanced data and statistical power
Although I have used R to explain my question, I think and hope this is of general interest and is not off-topic here.
I want to test whether the continuous variable “varA” is different between the ...
- 81
1
vote
0
answers
153
views
Inflated Type 1 error in glmer (for main effect but not interaction?)
I am doing simulations of type 1 error, power, and power' (power corrected for anti conservativity) for research on a specific application of (g)lmer, namely to small-N designs of longitudinal ...
- 55
1
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0
answers
387
views
Retrospective power analyis of lmer for sample size
I'm an MSc student doing an assignment where I am asked to analyze and write up a report on a dataset on environmental enrichment in zebra finches. Among other things we are being asked to do a ...
- 11
30
votes
3
answers
39k
views
Sample size calculation for mixed models
I am wondering if there are any methods for calculating sample size in mixed models? I'm using lmer in R to fit the models (I have random slopes and intercepts).
- 713