# longitudinal

1. ### Change score an independent variable in mixed model

I have an (ordinal) outcome measured at two time points, baseline and year 1. My colleague is interested in how our exposure variable is associated with the outcome after adjusting for a number of covariates captured at baseline. However, our exposure variable is a percentage change from...
2. ### Longitudinal Mulitlevel Model and Complex Survey Design in R Studio

I'm using multiple waves of the United Kingdom Household Longitudinal Survey (also known as "Understanding Society Survey") and want to use mulilevel models to explore change in health within individuals and between individuals. As far as I understand using a simple two-level model would mean...
3. ### Mixed Modelling for Longitudinal Research

What does random intercept and random slope mean in terms of longitudinal research?
4. ### What statistical test should I use?

Hello, I am currently working on my thesis proposal and am having to state the proposed methods of my data analysis. I am focusing on two aims: 1) analyzing whether individuals with metabolic syndrome have higher rates of depression; 2) analyzing whether individuals with metabolic syndrome...
5. ### Multivariate Linear Regression

I wonder if anyone can help me. I am trying to do a multivariate linear regression, I have 3 dependent variables with 2 separate time points for each, how do I condense this into three variables so that I can look at the time points together.
6. ### Hypothesis difficulty

Let Y_{ij}=1 if the i^{\text{th}} child is classified as obese at the j^{\text{th}} occasion, and Y_{ij}=0 otherwise. The marginal probability of obesity at each occasion follows the logistic model log\frac{\Pr(Y_{ij}=1)}{\Pr(Y_{ij}=0)}=...
7. ### Variable selection with longitudinal and correlated data

Hi, I'm working with a high-dimensional medical database, with detailed monthly medication reimbursement data as well as occurence of diverse medical outcomes, over several years (2010 to 2013). My database is composed of about 600 000 subjects. My goal is to identify associations between...
8. ### How to do Mediation across pre-post timepoints?

Hi all, I am looking into analyzing potential mediation and not sure how to approach it with two timepoints. For some context, participants are measured at two timepoints: pretreatment (T1) and posttreatment (T2). All participants receive the same treatment. At pre and post, they complete...
9. ### longitudinal multivariate data - multivariate repeated measures

Hi! Am dealing with a multivariate longitudinal data where we collect data from two group of subjects (cases and controls) at baseline , one month , two month, and at three months . At each of these four time points we collect data (which basically consist of 4000 variable of which many of...
10. ### Longitudinal weighting

Hi all. Wish you all well. I have to do weighting for an alcohol longitudinal study(2011-2013). How do I go about getting the final weights? Some people stopped responding as the survey progressed leaving only the drinkers responded in the end(2013). Does it sound statistically right...
11. ### Conducting longitudinal interaction analysis, using bootstrapping.

In relation to my dissertation, I am looking for someone with the competences to perform interaction analysis in m plus on longitudinal data, with the use of bootstrapping and checking for potential level 2 clustering effects. I would offer authorship on the article and / or payment. If someone...
12. ### SEM CFA results in error for longitudinal data

I am trying to build a longitudinal measurement model of a "strategy construct" using SEM. As long as I am building the model for each year individually, I have no problem and Stata's SEM converges. I use the following code...
13. ### Longitudinal analysis across age, when participants are all different ages from T1

Hi all! I'm looking to do a longitudinal analysis to see how a variable changes across two time points. The thing is, from T1, my participants are all different ages (between 5 and 10 years). I've done a regression at T1 for a cross-sectional comparision, but I would really like to...
14. ### HLM-Longitudinal Analysis: Moderation in level 2 variables?

Hi, I am creating a growth model using HLM 7 where Level 1 is Occasion and Level 2 is Person. I am trying to see if I can test the moderation effect of one level 2 variable on another level 2 variable (does propensity for excitation (L2) moderate the effect of mood (L2) on arousal over...
15. ### Compare Treatment Effects of 2 Groups - Repeated Measures & Binary Outcome

Hi, I have two groups (1:non-comorbid group, 2:comorbid group), where patients in one group have a condition that patients in the other group do not have at baseline. I want to compare risk factors among these groups on a binary outcome using longitudinal data. In other words, I want to...
16. ### comparing change from baseline (two treatment groups, binomial data)

I am comparing the effectiveness of a vaccine in reducing the prevalence of the targeted protein. I have baseline data (before the vaccine was even available), and now have data from vaccinated and non-vaccinated individuals. I have used chi-square/odds-ratios to show that the prevalence of...
17. ### Longitudinal multilevel moderation analysis - stats geniuses, please help me!!

Hi all, I am working on a very complicated analysis and am quite lost! :confused: I am analysing data from a randomised controlled trial. I have 3 groups (treatment 1, treatment 2, waitlist), and 3 repeated measures (baseline, time 1, time 2). In addition, I have 7 possible continuous...
18. ### Longitudinal analysis - what to do with the baseline data?

Hi, I have posted previously but got no response - so I am trying to narrow my search field down and articulate my questions better. If I am doing a longitudinal analysis looking at the trajectory of a dependent variable (y) over time (x) - but I have baseline measures of y at x=0-1 to...