All Questions
3,928 questions
5
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Visualizing the folly of fitting random slopes for variables that don't vary within groups
Sometime I encounter wrong mixed-models that run without warning. By wrong, I mean logically nearly impossible. Think of a cross-level interaction that is set by the software syntax to AGAIN vary ...
- 4,056
5
votes
1
answer
246
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Different fixed effect models
I am stuck at understanding the difference between different types of fixed effect models. In particular, what is the difference between:
A two way fixed effect model in the form of $$y_{it} = \...
- 387
5
votes
2
answers
460
views
Is appropriate to use empirical Bayes (EB) in this way?
Background. I have data from a study where participants make a series of judgments (a series of decisions with a binomial outcome, either $y=1$ or $y=0$). I have a model of the underlying decision-...
- 3,275
5
votes
2
answers
194
views
In Bayesian statistics, what does this notation formally mean?
I've seen Bayesian models specified as
\begin{align*}
Y_i|v_i &\overset{ind}{\sim} f_i(y_i|v_i),\\
v_i & \overset{ind}{\sim} g_i(v_i).
\end{align*}
My question is about the top line $Y_i|v_i\...
user209990
5
votes
2
answers
368
views
Multi-level data vs multi-level models
I am confused about the applicability of linear multi-levels models (also called hierarchical linear models or mixed-effect models) on data with multiple levels. At first, I thought they are made for ...
- 2,096
5
votes
1
answer
1k
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Can a ROC AUC curve look like this?
What are the possible shapes of an ROC curve? Is it necessary for an ROC curve to be shaped like a normal distribution curve?
Can we regard the following two curves as ROC with the area under the ...
- 479
5
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2
answers
78
views
Have population, use inferential statistics? Also, non-normal dependent variable, what to do?
Background: We are looking at parental leave in Iceland. We are particularly interested in whether the economic crisis and the resulting changes in parental leave legislation affected the time taken ...
- 51
5
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2
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11k
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Is automatic linear modelling in SPSS a good or bad thing?
In SPSS Version 19 there seems to be a new feature called Automatic Linear Modelling. It creates a 'Model' (which is new to me) and the function seems to combine a number of the functions that is ...
- 131
5
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2
answers
440
views
Where does multilevlel modeling fit in with causal inference?
I am just now exploring the world of multilevel modeling and I am wondering how to contextualize MLM within the broader toolkit of causal inference techniques. In one of my graduate econometrics ...
- 825
5
votes
1
answer
226
views
Why does the survey package in R and SPSS complex samples add-on give different standard errors?
I was comparing results that I generated in R for complex survey analysis using the survey package to results from SPSS using the complex samples analysis add-on. The sample size is large ~ N=5500
...
- 467
5
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2
answers
211
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Choosing a linear model to take into account multiple observations from the same individuals
I’m looking at how temperature varies across age. Can you help me to choose the most appropriate linear model to this analysis?
I’ve got multiple measures from 1 individual per age (13 in total), and ...
- 63
5
votes
3
answers
276
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Counting Biased Coins
Edit Note:
While this question is very interesting and relevant in its own right, I have come to a realisation that I have to make it a bit more complicated in order for it to be applicable to my ...
- 2,131
5
votes
2
answers
1k
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Using random effects to adjust for cluster-level confounding?
There is a usage of random intercepts to adjust for unobserved cluster-level confounding, as for example argued here:
Are random effects confounding variables?
How do random effects adjust for ...
- 1,149
5
votes
1
answer
4k
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Why is ANOVA interaction no longer significant after including a covariate?
I have initially run a 2x2x2 Anova and found some significant interaction between the independent variables. I then ran a ANCOVA where I added a covariate. I am confused with how to interpret the ...
- 51
5
votes
1
answer
7k
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Variances not homogeneous problem in ANOVA mixed between-within subjects, too bad?
I'm conducting a 2x3 mixed between-within subjects ANOVA (group x time). I have 20 participants, 10 for each group, who undergo all the 3 measures over time.
Levene's test of equality of variances is ...
- 173
5
votes
1
answer
233
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Multilevel Model or Simple Correlation Coefficients
I am interested in the relationship of several variables (questionnaire score = q1 (0-24); physiological measures = phys) across consecutive conditions (block = 4 consecutive conditions) and between ...
- 51
5
votes
1
answer
165
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Intercept interpretation in multi-level model when first-level predictor discrete
This is the experimental setup:
1 dependent variable (discrete, 4 levels) and
3 Independent variables:
Time, measured within subject, 5 discrete levels
Covariate, measured within subject, 5 discrete ...
- 415
5
votes
2
answers
8k
views
How are confidence intervals for proportions computed under SPSS?
I wonder whether any of you can help me. SPSS puts confidence intervals in graphs of frequencies and proportions,
but it clearly is not using a normal approximation, i.e. it is not using the formula $\...
- 51
5
votes
1
answer
75
views
How to translate hierarchical linear model random effects into SEM path diagram?
I've been struggling with translating random slope and intercept and random variables and understanding them as latent variables in the pursuit of path models.
For example here is a random slope and ...
- 704
5
votes
2
answers
117
views
SPSS and PSPP yield very different logistic reggression results with same dataset
I'm trying to run a multiple logistic regression model where the dependent variable is dichotomous and independent variables are either bynary or continuous. At first I only had access to PSPP, but ...
5
votes
1
answer
1k
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Changing the time metric for longitudinal data
I have some longitudinal data. I've done longitudinal analysis before but I have never changed the time metric so I wanted to run the process of that by you.
Edits for clarity:
I have repeated ...
- 53
5
votes
2
answers
379
views
Multilevel models for groups that have different predictors
Imagine I am trying to fit a multilevel model on products, and want to group by product type.
In cases where product types have all the same predictors this is straight-forward. E.g. you might ...
- 231
5
votes
1
answer
244
views
Book recomendation introducing multilevel models for a pure mathematician
Is there a good book on Multilevel models (random intercept, random slope, fixed effects, etc.) written for mathematicians which treat the theory rigorously?
My background is essentially is in the ...
- 213
5
votes
1
answer
548
views
How to interpret main effect with two interaction terms?
I have three variables in a multilevel model:
Relationship Status (0 = single, 1 = not single)
Living Arrangement (0 = alone, 1 ...
- 235
5
votes
1
answer
1k
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Are time points nested in students or crossed in a longitudinal multi-level model
I often hear that in a longitudinal multi-level analysis, time points (as a fixed factor) are "nested" within students (e.g., just search the word $nest$ in this paper).
However, this great ...
- 4,056
5
votes
1
answer
1k
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$R^2$ for mixed models = ICC?
I will be referring here to Nakagawa and Schielzeth (2013). As those authors state, $R^2$ for OLS regression could be defined as follows:
$$R^2 = \frac{\sum^n_{i=1}(\bar{y} - \hat{y_i})^2}{\sum^n_{i=...
- 141k
5
votes
2
answers
2k
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interpretation of correlation matrix of regression coefficients in Cox regression?
I am using SPSS to perform Cox regression. After finding all the significant covariates, there is a table called correlation matrix of regression coefficients.
My question is what kind of information ...
- 61
5
votes
2
answers
414
views
Finding latent variables in 7 dichotomous variables
I have read other posts on conducting Factor analysis (FA) with dichotomous variables and although it appears clear that FA done in the default way is not appropriate, I am still unclear about a few ...
- 333
5
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1
answer
3k
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How to calculate weighted Hedges' g effect size in meta-analysis when some effect sizes share a control group?
I am trying to do a meta-analysis using Hedges' G as the effect size.
Questions
Some of the studies have different groups but the same control group. How does this change the computation and ...
- 51
5
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1
answer
1k
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Misspecified levels in multilevel mixed logit model
I'm estimating a couple 3 level logit models using Stata 12 and am faced with a dilemma about how (or if) I should specify my third level.
The data is court cases nested within judges nested within ...
- 538
5
votes
1
answer
124
views
Testing for the effect of an intervention when it is applied on a group of which each individual is measured
Suppose we have 500 students nested in 20 classes (different classrooms), 25 students per class
student<-factor(1:500)
class<-rep(LETTERS[1:20],each=25)
...
- 3,191
5
votes
1
answer
3k
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Multi-stage selection model with panel data in R
My data consists of individual level observations nested within countries over time. I would like to use multilevel models along with some sort of selection model.
I have three related questions.
...
- 285
5
votes
1
answer
912
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Between- and within-person level effects when using multilevel modelling for longitudinal data in R
I’m using nlme package in R for analysing longitudinal data. The aim is to understand if changes in need satisfaction (TNS) and ...
- 53
5
votes
1
answer
1k
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Dealing with heavy-tailed residuals when fitting hierarchical linear models using lme4
This is my first time posting, so please excuse any issues with respect to my description of the problem and the presentation of the data and code I have supplied.
Summary of the Design
30 listeners ...
5
votes
2
answers
2k
views
Standard deviation as dependent variable inside a HLM
I'm not a statistician so maybe my question is very simple but I've encountered some difficulties reading a statistical method in a cognitive psychology paper.
Basically the dependent variable to ...
5
votes
1
answer
1k
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Reconciling various definitions of Variance Components
In the context of multilevel modelling, Field (2013) p. 827 provides the following representation of a variance-covariance matrix to illustrate Variance Components
and writes
This covariance ...
5
votes
1
answer
690
views
Calculating variance components and ICC of a random intercept model by hand
When I really want to understand a measure or parameter, I tend to do the calculation by hand with simplified data. Today I have attempted to do the same with the ICC, but somehow keep failing. I was ...
- 81
5
votes
1
answer
8k
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Assumptions of multilevel analysis
In response to another question StasK writes:
In multilevel analysis, you have to make strong assumptions: (i) that
your random effects are normal (or, if you have random slopes as long
as ...
5
votes
1
answer
7k
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How to model percentage dependent variable using logistic regression in spss
I have some aggregated data.
Indep. Dep. N
1.3 78% 23
1.2 67% 20
Indep var the average score of people in a particular region. Dep. var is ...
- 1,197
5
votes
1
answer
416
views
Variant of discriminant analysis for known multiple independent classifications?
I have a large data set: over 100,000 data points, each with 60 dimensions. I want to display the data in 2D to visibly maximize the separation between classes, which I know for each point. I asked a ...
- 143
5
votes
2
answers
228
views
Comparing weights in SPSS regression and R lm
In SPSS, you can use a variable as WLS Weight when carrying regression.
In R, you can use a variable as an argument weight in <...
- 688
5
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1
answer
587
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What is a two-stage regression, as a prelude to multilevel modeling, concretely?
I would like to fit some multilevel models to my data. In several places Dr. Gelman has suggested that one can fit a two-stage regression as a prelude to a multilevel model, to see if a more flexible ...
- 772
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1
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483
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How to do classification in mixed effect models in python. My data is nested into groups with binary outcome
Lets say I have 10 sellers (S1-S10). Each seller has 7 buyers which are different for each seller (B1-B7 for S1, B11-B17 for S2 and so on). Each Seller buyer combination has a product category (P1, P2....
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5
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2
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1k
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With two related variables, eg, religion and religiosity, how do I transform them into one variable for regression?
Say I have the nominal variables of religion (0=Athiest; 1=Christian; 2=Jewish; 3=Muslim; 4=Other)
And then a scale variable of religiosity from 1-10
If I want just one scale variable, so that I can ...
- 313
5
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1
answer
13k
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How to Graph Moderation Effects on SPSS
I am conducting an independent research but am completely stuck on how to visualize my data.
So I am looking for a moderation effect of peer sociometrics (ex. negative nominations, social preference)...
- 51
5
votes
1
answer
1k
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Can Amos SEM deal with binary dependent variable?
Hi I'm doing a SEM using AMOS. The outcome is the success of consumer satisfaction, which is measured by 2 questions.
How satisfied are you? (1-7)
How likely would like to recommend ? (1-10)
If ...
- 301
5
votes
1
answer
3k
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Factor analysis with repeated measures
Multilevel factor analysis seems to be the technical term for factor analysis with repeated measures, judging from this abstract. To be precise, following Wikipedia's factor analysis notation, the ...
- 2,160
5
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1
answer
4k
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Multiple weights in multilevel models
I am currently working on a random intercept multilevel model using the European Social Survey round 6 dataset. It is a 2-level model with individuals (level 1) nested within countries (level 2). To ...
- 125
5
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1
answer
78
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Method/workflow for analyzing data with changing structure?
I am analyzing data relating to networks that evolve over times (more precisely, a snap shot of the network at every discrete time step). Each node of the network denotes a person who perform some ...
- 301
5
votes
1
answer
3k
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What does the Scale parameter mean in linear regression?
I have started to use the GENLIN procedure in SPSS more than any of the specific dialogues, but I don't understand the Scale parameter or why it has the effects it ...
- 1,803