longitudinal data

  1. M

    Longitudinal multilevel modelling- Can likelihood ratio tests be done for time-varying predictors?

    Hello, I plan on using likelihood ratio tests for longitudinal multilevel modelling and using a mixture of static predictors and time-varying predictors. I know that likelihood ratio tests are used for 'nested' models for static predictors when a new static variable is added to the model and...
  2. L

    Three-way interactions with longitudinal data

    Hi there, We are trying to examine whether carrying the risk gene for Alzheimer's disease (E4), moderates the effect of a continuous predictor over time (c.RNT#c.Time), on global cognition. In other words, "does carrying (or not carrying) the E4 allele moderate the effect of RNT on global...
  3. V

    Visualizing longitudinal data

    Hello, How can I visualize my longitudinal dataset? I have a dataset in which I am interested in seeing the variation of the presence of metabolic syndrome over time for each participant. There are approximately 1,083 participants in my dataset with 1-8 visits each; there is a total of 3,090...
  4. D

    Comparing effect sizes of two longitudinal linear relationships

    Is there a way to determine if one longitudinal linear relationship is significantly stronger than another? I was planning on using regression (moderated multiple regression with PROCESS macro for SPSS because I have two groups and covariates) and simply looking at the R squared values, but my...
  5. kiton

    Seeking advise on predictive modeling approach

    Hello dear forum members! Currently, I am working on a project that aims to predict a certain cancer-related outcome (y) using a number of control (c) and predictor (X) variables: y(i) = a + c(it) + X(it) + u (1) In Equation (1): y(i) is continuous in nature, data is available only...
  6. C

    Does Imposing a Constrain Make a Method More Powerful?

    Suppose we have 100 patients in a randomized trial. 50 of them are in treatment group and the rest are in placebo group. This is a longitudinal study so that we measure the response from each individual at four different periods: baseline, week 1, week 4, and week 6. Now suppose we have good...
  7. I

    Correcting for regression to the mean in mixed effects model of longitudinal data?

    Hey everyone, I know you can correct for regression to the mean for two time points, in a before and after scenario. But does anyone know how to do this when there are more than two time points, let's say there are about 10 points in a time series. I was hoping to model the longitudinal data...
  8. A

    What test to use for longitudinal data and to test interactions among factors?

    My study involves five plant varieties subjected to three cultivation methods in two different sites. Every week for six weeks, we record the specific daily growth rate of all the plants. I’d like to analyze differences in growth rates in terms of variety, cultivation method, sites, and time...
  9. P

    Mixed models can variable be both fixed and random

    I am conducting an analysis over multiple subjects over several sessions with two types of controls. I want to conduct a mixed model analysis to see if there is a difference with respect to control type. This is what i have so far: I have session nested in subject. Accuracy= dependent variable...
  10. O

    Longitudinal analysis of drug use data

    Hi all, I'm looking to conduct a longitudinal analysis using data from 5 waves of an observational research study. What I'm really interested in doing is seeing how changes in parental monitoring and some other family factors (i.e., cohesion, etc.) impact drug use and negative consequences of...
  11. T

    Factor Analysis / PCA with longitudinal data

    Hello, I have a problem which I'm trying to get around... I am trying to conduct a principal component analysis which compares changes in labour market regulation in the EU pre and post financial crisis. The first problem I faced was a low sample size as my sample size initially concerned just...
  12. S

    longitudinal dataset (vertical format): create tree diagram of change at timepoints

    Hello friends, I have a very complex syntax question I believe may even stump the very best of you! I have a longitudinal dataset measuring depression level on a 3 level scale (none, moderate, severe). The dataset is currently in vertical or 'stacked' format. I am to create a tree...
  13. S

    Vertical-Format longitudinal dataset: Fill in missing values for cases

    Hi all, I am running some growth curve analysis in SPSS. My data is in the vertical/stacked format. There are 6 entries for each person since we measures six points in time. HOWEVER, my model won't run because there is too much missing data. This is because for the demographic data...
  14. N

    overall model fit for generalized structural equation model

    Hi All, I'm new to this forum, and I hope I can be both of help and find help. My current problem involves modeling longitudinal data. I have four waves of data and I'm examining employment status and rearrest as endogenous outcome variables. I have built and run a generalized structural...
  15. A

    Choosing test for longitudinal, repeated measures and clustered data

    Hi everyone! I'm a researcher within cardiovascular medicine, currently working on a study in endocrinology (diabetes). I have the following challenge, which I have discussed with several staticians who all gave me discordant advice and explanations (which is why I'll try the discussion...
  16. S

    Regression diagnostics on panel data regression

    Hey guys. I've not worked much in panel data regression but what I've been thinking about (and not been able to find much information about) is post diagnostics for fixed effects panel data regression (yit = alpha + XB + ui + eit). Is it possible to be able to do residual analysis...
  17. S

    Long to wide

    Hey guys. I''ve finally gathered the last of the data I need to do some longitudinal research but then I hit a snag. As far as I know, my data is on long format and someone told me, that it needs to be in wide format. Now I just have one variable for year, one for country (dummy) and then a...
  18. A

    Advice on linear mixed model on longitudinal data

    Hello, I have a longitudinal dataset of cumulative biomass from an experiment. The subjects have been exposed of 3 different treatments (LOW, MED, HI) during 194 days, and measured repeatedly at 40 occasions. According to my plot, it looks like one of the HI treatment is starting to differ...
  19. N

    testing different models using the same group of longitudinal data

    Description of my research Longitudinal growth data are fitted using parametric models giving growthcurves. Differentiating these growthcurves gives velocity curves. From every curve biological parameters can be determinated. Every parameteric model has function parameters. The same...
  20. O

    Writing equations for latent growth curve models

    Hi all, I'm a PhD student currently working on an independent research project using latent growth curve modeling. This is my first time using this statistic, and I was wondering if anyone had a good reference that discusses how to form the statistical (i.e., mathematical) equations. I like...