All Questions
Tagged with mixed-model hypothesis-testing
146 questions
2
votes
0
answers
14
views
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 ...
- 882
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 ...
- 11
4
votes
1
answer
66
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What should I call this design?
Tha someone help with this question?
A study has 3 fixed effects A, B, and C and one random factor ID. Factor C (two levels) is determined by each ID's inherent characteristic (so basically two groups)...
- 119
1
vote
1
answer
55
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Two way anova or paired t-tests
i am looking to see if there is a difference in dissolved oxygen levels between pool surface (S) and bottom (B) samples at four sites (an up and downstream site in two creeks). There are 3 replicate ...
- 11
7
votes
2
answers
171
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(Mixed-)model specification and comparison for testing hypotheses concerning continuous ratings
In a behavioral study following a within-subjects design, subjects of various levels of musicality (years of education) gave continuous liking ratings of three audio stimuli, each under three ...
- 2,352
3
votes
1
answer
67
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Choose to resolve and report only some hypotheses
I have carried out a 2 x 2 x 4 x 4 experiment with 12 subjects to perform a linear mixed model. Would it be correct to perform the complete analysis but report only the results of the 2 x 2 ...
- 91
1
vote
1
answer
30
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Testing the effect of a continious IV on DV, in order to explain group differences
I would like to ask a question regarding an analysis I’m planning and it might be a basic question so, apologies in advane.... To describe the situation: There are two groups of participants in my ...
- 31
5
votes
2
answers
796
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Different results between ANOVA and Linear Mixed Effects
A set of subjects from two groups are requested to perform a test after a sleep session of type A and then after a sleep session of type ...
- 235
2
votes
2
answers
246
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Determination of sample size vs. repeated measurements in experimental design
NOTE: Revised question following suggestions from others. Thank you for taking the time to help me refine this question to make it answerable!
Background
I want to compare the performance of two ...
- 71
5
votes
1
answer
53
views
Is repeated measures appropriate for testing for a difference in repeated paired group measurements?
I'm new to repeated measures and am trying to understand how it maps to lmer.
I have measurements from two time periods:
$t_1, t_2$.
At each measurement period, the same 50 different foods are scored ...
3
votes
1
answer
217
views
Mixed effect logistic regression model
I am very new to the world of statistics and I need some help. I am currently doing an experiment and I have to analyze the data, but I honestly do not know anything about statistics (I have tried to ...
- 175
100
votes
11
answers
280k
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How to obtain the p-value (check significance) of an effect in a lme4 mixed model?
I use lme4 in R to fit the mixed model
lmer(value~status+(1|experiment)))
where value is continuous, status and experiment are factors, and I get
...
- 2,201
2
votes
0
answers
70
views
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
0
votes
1
answer
44
views
Test for significant difference between two groups measured across time
I have two groups of time-dependent samples whose measured value changes nonlinearly with time. There are 3 samples in group A and 3 samples in group B. An example of my data is illustrated below.
...
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3
votes
1
answer
696
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Understanding Mixed Effect Models visually with some questions on P-value calculations
I've been tackling the concept of Mixed Effects Models on and off for the last 9 months. Every time I would give up and come back later to try and understand it again with my basic statistics ...
- 145
1
vote
0
answers
65
views
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 ...
- 13
1
vote
1
answer
92
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I think this data should be analysed using a linear mixed-effects model, but it doesn't seem to make sense when using buildmer? [closed]
I can't give the exact data because it's sensitive, but I have the following information about the data:
3 continuous variables which are within subjects (scores for test separated by time).
1 ...
7
votes
1
answer
127
views
Explaining a Mixed Effect Model to a Non Statistician/Mathematician
I'm not a statistician, but I do have a basic understanding of biostatistics in the context of medicine and clinical trials. However, recently I came across a trial that is using a statistical method ...
- 145
2
votes
1
answer
76
views
Paired t-test on dependent samples
I have a set of paired observations, corresponding to patient blood pressure before and after a treatment. I'd like to test for the significance of the treatment by conducting a paired t-test (or ...
- 23
4
votes
1
answer
262
views
What kind of model is best suited for this type of data and research question?
I have data for hundreds of individuals over several (often tens) of years. My dependent variable is a binary event that may or may not have happened for each individual in some given year. The event ...
- 73
35
votes
3
answers
53k
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How to get an "overall" p-value and effect size for a categorical factor in a mixed model (lme4)?
I would like to get a p-value and an effect size of an independent categorical variable (with several levels) -- that is "overall" and not for each level separately, as is the normal output from ...
- 1,345
0
votes
1
answer
366
views
Incorporating a random effect to the null model
I would like to decide if it is reasonable to include a factor variable to the null model I.e y ~ 1 VS y ~ (1|x)
I haver read this answer https://stats....
- 1,699
17
votes
3
answers
2k
views
Should "City" be a fixed or a random effect variable?
I am analyzing data on "BloodSugar" level (dependent variable) and trying to find its relation with "age", "gender" and "weight" (independent variables) of ...
- 10.2k
0
votes
0
answers
16
views
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 ...
- 31
0
votes
0
answers
43
views
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 ...
-1
votes
1
answer
83
views
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 ...
- 49
1
vote
1
answer
68
views
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 ...
- 11
2
votes
1
answer
127
views
How to analyze a dataset with unequal treatment distribution?
I’m looking for the best way to analyze a data set. The experiment was conducted at two different locations, X and Y. The experiment at location X was conducted in one year (2014), whereas the one ...
- 435
1
vote
1
answer
40
views
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 ...
2
votes
2
answers
493
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Working with Discrete-Time Survival Analysis with Random Factors in R
I'm working with some data on artificial (fake) bird nests, looking into their 'survival' from animal attacks. I visited the nests once every two days, for 2 weeks (so my time points are 2,4,8,10,12,...
- 41
9
votes
2
answers
4k
views
Obtaining p-values in a robustlmm mixed model via Satterthwaite-approximated DFs of the equivalent lme4 model?
I've used lme4 to fit a mixed model and could obtain p-values by using the lmerTest or afex packages. However due to heteroskedasticity (Levene Test) I also fit a robust model (rlmer command in the ...
- 383
2
votes
1
answer
128
views
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
1
answer
92
views
Which test would take advantage of comparing large sample groups with replicates?
So, the data is comparable to height of individuals within Africa and Europe, but each group (Europe, Africa) have multiple replicates (3 x month sampled).
Each replicate is ~100,000 individuals.
A ...
- 21
3
votes
1
answer
62
views
Should all the levels of a fixed factor be present in all the experimental trials?
I would like to analyze the output of 11 field trials dealing with the disturbance to soil after logging operations. The goal is to check if there are significant differences between two machinery: ...
1
vote
2
answers
4k
views
Hypothesis testing with control and treatment group - which statistical analysis to use?
I would like some advice on what statistical analysis to use to test my hypothesis. I am using R. My setup is as follows (in .csv format, first line is header):
...
- 81
1
vote
0
answers
44
views
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 ...
- 111
9
votes
1
answer
773
views
Confused: Why is lme4 changing techniques from Wald F tests to Wald Chisquare?
I've constructed some LMEMs that use dichotomous variables and their interactions as regressors, and I've become confused by the output. When I only assess a single interaction, using the code below (...
- 129
3
votes
2
answers
324
views
What statistical test should I use with count data? [duplicate]
In my experiment, participants are shown 4 images (A, B, C, D) that they have to rate on a 5 point scale. So my data looks like this:
particpant1: A 5, B 3, C 3, D 1
p2: A 4, B 3, C 2, D 4
p3: A 4, B ...
- 37
1
vote
0
answers
1k
views
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 ...
- 141
2
votes
1
answer
2k
views
Mixed effects model adding covariate vs adding random effect
I am currently looking into mixed effect models and I am trying to understand the difference between adding a random effect and adding a covariate to a linear model.
Consider this example:
...
- 27
5
votes
1
answer
555
views
Paired and repeated measures! Now what? ANOVA or mixed model?
I have a simple setup. I have 10 patients and I would like to test the effect of a certain drug on kidney function. Each patient will serve as his own control and intervention.
First for the control ...
- 85
2
votes
1
answer
77
views
hypothesis testing with data that are not equally independent
I think the easiest way to explain my question is with an example scenario:
Let's say we have 10 groups of 5 people and each group is in an identical circular room in which we are allowing them to ...
- 107
4
votes
2
answers
6k
views
Linear mixed model in R; modelling fixed effects with multiple levels and interactions. Help!
I am new to R and to mixed linear modelling. I have a dataset with variables from a cross-sectional study looking at fractional anisotrophy (a property of the brains white matter) in 6 different white ...
2
votes
2
answers
573
views
Interpretation very small standardized coefficient beta
In one of my studies I have results similar to the below:
β=-0.0007 (95% CI: -0.0009, -0.0002), p=0.01
Since β is so small (but also the Confidence Interval (CI)), is this result still meaningful?
...
- 51
7
votes
1
answer
5k
views
Big difference between a t-test and a F-test in a mixed model (anova vs summary in lmerTest)
While helping someone else with their analyses, I've run into a question regarding the difference between t-tests and F-tests for linear mixed models in lme4 for R, as provided by lmerTest. I'm aware ...
- 237
2
votes
1
answer
224
views
How to simulate type I error for random-effects model?
Building upon this post How to simulate type I error and type II error. I would like to simulate type I error for a random-effects model I generated. The statistic of interest is standard deviations ...
- 211
3
votes
1
answer
204
views
What statistics can be used to analyze and understand measured outcomes of choices in binary trees?
I am conducting biological research on animal behavior. There is an arena set up like a binary tree. End nodes are sources of food (e.g. smells) or stimuli that can mix. The animal (or a group of ...
- 31
15
votes
1
answer
16k
views
Conflicting results of summary() and anova() for a mixed model with interactions in lmer+lmerTest
I recently came across what I think may be a problem in how the anova() function from the lmerTest packages computes its F-...
- 451
0
votes
0
answers
30
views
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
29
votes
2
answers
15k
views
How should mixed effects models be compared and or validated?
How are (linear) mixed effects models normally compared against each other? I know likelihood ratio tests can be used, but this doesn't work if one model is not a 'subset' of the other correct?
Is ...
- 2,842