All Questions
Tagged with mixed-model hypothesis-testing
50 questions with no upvoted or accepted answers
4
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0
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Testing Fixed and Random Effect of Mixed Model
This pdf illustrates nicely how is to test the random effect of multilevel model . But I am simulating data from a two-level model and estimating the parameters of the model for various combination of ...
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4
votes
0
answers
313
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Compare sample means of normal distribution with autocorrelation issues
Please forgive me if this is a naive question, but I haven't been able to find an answer in my stats books or online. I'm working on a fish tracking dataset that consists of detections of tagged fish ...
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3
votes
0
answers
165
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Is there a joint test of model coefficients, effectively testing for main and interaction effects in quantile linear mixed model?
I am just reading this paper: Linear Quantile Mixed Models: The lqmm Packagefor Laplace Quantile Regression. Let us assume I have a repeated observation experiment, where I want to assess the effect ...
- 123
3
votes
0
answers
572
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union intersection test and likelihood ratio test
I am a bit puzzled by a result I got in linear mixed effect regression.
Let the systematic part of the linear mixed effect model be:
$$
Y = b_0 + b_1X_1 + b_2X_2 + b_3D_2 + b_4D_3 + b_{12}X_1X_2 + ...
- 31
2
votes
0
answers
70
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How well does my model fit? Specifying a null-model in non-linear mixed models
I want to fit a model y ~ b * exp(-exp(a) * x), but including a random effect, with this data:
...
- 33
2
votes
1
answer
128
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Correct inference on hierarchical data
I am doing an experiment on cell cultures comparing how some treatments affect the parameter of the cells. I have 3 replicates of the culture for each treatment, and in each culture, I measure the ...
- 43
2
votes
0
answers
244
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Why duality of confidence interval and hypothesis testing fails in random effect test for presence random effect?
I am reading Faraway's Extending the linear model with R chapter 10 section 2.
"In this case, the lower bound is zero. This is not surprising given our earlier
uncertainty over whether there ...
- 1,465
2
votes
0
answers
198
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Testing for between-samples factor with linear mixed models
I have data from an experiment including 5 biological replicates, each of which has 3 technical replicates. These 5 samples are divided into 2 groups (condition a and contidion b). My goal is to test ...
- 21
2
votes
0
answers
451
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How would I conduct an equivalence test in R from an lmer() model?
Lets say I have a null result, as in the following example:
library(lme4)
iris$Rand <- rnorm(150)
m <- lmer(Petal.Width ~ Rand + (1|Species), data = iris)
...
- 2,701
2
votes
0
answers
71
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Hypothesis testing : Constant mean over time for two conditions within an experiment
What is an approach to testing/showing that within a particular period of time, there is no change in values. So, I have my response variable measured over 30 seconds, in two conditions. I want to ...
2
votes
1
answer
39
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Analyse variation between distribution curves according to factors
I have a set of continuous distributions representing the leaf area density found at different heights through a forest canopy. e.g. like that found in Whitehurst et al. (2013):
For each of these ...
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2
votes
0
answers
2k
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Satterthwaite degrees of freedom in lmerTest for a 3x2x2 mixed model vs. mixed ANOVA dfs
I have traditionally been running my analyses using aov and would like to switch to lmer. My questions is whether or not this is ...
- 613
2
votes
0
answers
1k
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Linear mixed models. how to test if a condition is different from zero.
I have two conditions, A and B (see the figure below).
I want to test if these conditions are different each other, if condition A is different from 0 and if condition B is different from 0.
I'd ...
- 301
2
votes
0
answers
129
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Post hoc comparisions in many groups
I met such problem. I have measured the respiration of animals in in 5 time intervals. Within each interval I have animals asigned to 4 treatments. In my main analysis I consider both: treatment and ...
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2
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0
answers
94
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How to analyze data with DV only measured at the group level and moderator measured at the individual level?
This may be a relatively simpleton kind of question to ask, as this forum seems to be rather statistically sophisticated, but I'm rather mixed up right now.
I ran a study that involved individuals ...
- 21
2
votes
0
answers
135
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Identifying when fixed effects have changed in a GLMM
I have a dataset spanning several years, that I have analysed year by year (using the same glmm model code) to determine whether the random effect (random intercept) has altered over time. I have ...
- 3,952
1
vote
0
answers
12
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Test of variance component in one-way random effects ANOVA
I have a question regarding the adaptation of the following to the test of single variance components laid out in Raudenbush and Bryk (2002, p. 63-64). The hypothesis is about a single component of ...
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1
vote
1
answer
29
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Statistical model / test for difference in change over time for two conditions
I have data from an experiment that looks like this:
rep 1 T=0
rep 2 T=0
rep 1 treatment
rep 2 treatment
rep 1 control
rep 2 control
0
3
3
7
2
4
1
4
3
8
1
4
...
...
...
...
...
...
The ...
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1
vote
0
answers
64
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Comparing mixed effect models fitted to two different datasets
I have two different time series data which are the results of running a simulation model with different sets of parameters and configurations. The datasets each contain 100 time series which indicate ...
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1
vote
1
answer
68
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Using one linear model to test multiple hypotheses
Let’s assume the following:
I have data of 100 subjects each performing 100 trials of a reaction time task
At each trial, I measured the reaction time (RT) and a specific brain signal (BS)
The RT and ...
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1
vote
1
answer
40
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Interpreting Mixed Model ANOVA
In a 3 (condition) X 2 (time) mixed model ANOVA. If I hypothesised that anxiety in group A will increase from time 1 to time 2 and my results found no significant interaction but a significant main ...
1
vote
0
answers
44
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Colinear nested variables and hypothesis testing for higher-level variable in non-randomized experiments
We have a study setup for testing a new learning treatment, which basically looks like this:
We have 4 tracks (same university course taught by different lecturers). In two of these tracks, the ...
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1
vote
1
answer
36
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What options does a person have for showing evidence in favour of the null hypothesis?
I have a linear mixed-effects model with a theoretically important null result. Of course a reviewer asked for a Bayesian approach to "show evidence" for it.
However I am struggling with ...
- 2,701
1
vote
0
answers
1k
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Using clmm() for ordinal dependent variables
I have a 2 (Complexity: 1=Simple vs. 2=Complex) by 3 (Type: 1=A vs. 2=B vs. 3=C) design, where each participant completed separate tasks counterbalanced across the 6 conditions, and then gave a rating ...
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1
vote
0
answers
26
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Fit one model or several models to maximize power for significance testing of slopes in a factorial design?
Problem
I need to perform a power analysis for a set of statistical tests. Each test is about a regression slope computed in a cell of a factorial experiment design. To minimize the required sample ...
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1
vote
0
answers
121
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R or Stata shortcut to significance test interaction term including restricted cubic splines?
I fit the following model in R using the lme4 package, which is a linear mixed effects regression of outcome "WT_abs_change" (absolute weight change) on various factors, including "ns(WT_dtime, df=3)*...
1
vote
0
answers
289
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Which of the (two) conflicting p-values should I use when estimating lmer using R
I've recently started using LMM which possibly gives me better insight into my DV. Only I got some contradictory data regarding whether some variable is significant or not.
The Us and Hed variables ...
- 31
1
vote
0
answers
90
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What statistical test is appropriate to answer hypotheses on seasonal and spatial differences?
First of all, I am very new to statistics, so this might be a very basic question but I could not find any answers to my question in other topics here.
I have a data set on microbial growth (...
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1
vote
0
answers
79
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hypothesis testing to remove predictor
If we're working with a linear mixed model (fixed + random effects, normality assumptions) and are interesting in testing whether or not we can remove a fixed effect from the model, since standard ...
- 381
1
vote
0
answers
579
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Mixed effects model - interpreting significant fixed effect coefficients with insignificant likelihood ratio test
I have a linear mixed effects (LME) model with a single nominal-valued fixed effect with 4 levels, and two nested random effects (measurements from cells at each level of the fixed effect, with ...
- 1,505
1
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0
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879
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Testing and correctly interpreting the significance of nested random effects
I'm building a series of relatively simple random effects models where we repeatedly measure a water quality variable, say conductivity (cond), in different watersheds (ws) and streams (st). Here, ...
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1
vote
1
answer
40
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How to test for relationship between cumulative intake and outcome over time in single arm study?
I have a one group trial with n = 100. I want to analyze the relationship between the accumulated amount of drug intake (continuous) and the effect (measured by symptom score).
For example, for ...
- 11
1
vote
0
answers
4k
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Hausman test VS Mundlak model; the choice between fixed and random effects
I am using panel data and I have to choose between fixed-effects and random-effects models.
I run the Hausman test, the H0 (i.e., the difference in the coefficients from the two models is not ...
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0
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0
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16
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How to get a site-adjusted (clustered) p-value
I'm working on a problem involving clinical trial data and am trying to account for the different clinics patients were treated at. In papers I've read, authors present p-values for differences in ...
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0
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0
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43
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Hypothesis testing with data which is both pair and repeated-measures
Suppose I conduct an experiment to test the hypothesis that treatment A suppresses protein X. I am fortunate in that I work on kidneys, which come in pairs, however I am unfortunate in that I don't ...
0
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0
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30
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Significant t-value but bayes factor showing favour towards null
I am currently trying to build linear mixed-effect model to compare continuous dependent variables between categorical independent variables (like conducting ANOVA), but with random factors (to remove ...
- 1
0
votes
0
answers
73
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How to compute Cohen's d and p-value for comparison of least squares mean from two different mixed models?
I have two randomly assigned treatment interventions (A and B), and two subgroups of individuals (X and Y). This is a longitudinal study with dropout. I want to test whether the outcomes of ...
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0
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0
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30
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What is a good model for this data?(plot attached)
I don't think a linear model would fit this? This is a change in the 'dependent' variable over trials in two conditions.
The hypothesis is that over trials the dependent variable reaches a tabletop/...
0
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0
answers
1k
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GLMM. Why are my confidence intervals so wide when my p-values are so small?
I am trying to find out whether there is a significant effect of Treatment (factor with 3 levels: GR, BC and WF) on the number of moths captured per night in a field experiment. I have 15 Blocks that ...
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0
votes
1
answer
189
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Control variable with different levels in Regression
I have an experiment with two conditions: Control and treatment groups. I am measuring how confident the treatment groups felt while answering the question. It is a three level indicator- not sure, ...
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0
votes
0
answers
30
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Aside from switching to a Bayesian approach, how can I quantify the strength of evidence for a null result of a linear mixed effects model?
I've run a linear mixed effects model with a null result that would be quite interesting for the field. Is there a test I can run that would bolster the claim that the two groups are indeed equivalent?...
- 2,701
0
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0
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3k
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Mixed models: Assessing significance of random effects
Edit: Just adding a relevant blog post that discusses checking if a random effect should be included or not, but my question is more specifically based on deciding if the intercepts and slopes of ...
- 556
0
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0
answers
57
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How to use bootstrap to do a hypothesis test in mixed models
I have a mixed model with multiple covariates. I want to test if some of the covariates are insignificant. Since I have mixed model the LR-test will result in a p-value which is too low, hence I want ...
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0
votes
0
answers
134
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Random Effects ANOVA with test for difference in variances
Say I have a study measuring a continuous endpoint for 3 sample assays on two days, i.e. before and after intervention. The measurements are performed several times by different people (repeated ...
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0
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0
answers
50
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Am I violating assumptions of mixed effects model?
I am using a mixed effects model to analyse data, but am unsure whether I am committing any violations due to the nature of the data I have.
My data comes from a game whereby people have to identify ...
- 35
0
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0
answers
165
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ANOVA comparison of non-significant mixed models
I have two nested mixed models: the difference in these models is the presence of one predictor variable (type). I used lmerTest ...
- 163
0
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0
answers
35
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Two stage model with a randomly transformed independent variable
Hi all and thank you in advance for helping!
I have three variables: $y$ the dependent count variable, $x$ the independent positive continuous variable, $U$ is the observation unit (and I expect a ...
- 335
0
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0
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151
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Age Interactions in mixed models
We are using a mixed model to describe trends as subjects age. We have multiple measurements per subject of a continuous outcome. We also adjust for the age at entry into the study. It is of ...
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-1
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1
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83
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Mixed Effects or other Model for Binary Interventions and Binary Outcome
I'm trying to understand the impact of 2 different binary interventions on the completion rate of around 10 courses. The courses all have different baseline completion rates. Intervention one was ...
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