longitudinal design

  1. P

    Computing sequential time variable- Long format

    Hi Everyone, I am currently looking at lung function decline/change over time. Lung function parameters such as fev1, fvc, fev1/fvc have been converted to z-scores . The data is in long format with each individual having more than 2 assessments until 4. Thus, each individual has data in 2...
  2. C

    Defining Contrast Matrix

    Suppose I have a binary Covariate X which is defined as X = \begin{cases} 1, & \text{if treatment group} \\ 0, & \text{if placebo group} \end{cases} The model is \mathbb E[Y] = \beta_0 + \beta_1X, where Y is a continuous random variable. If X=0, then \mathbb E[Y] =...
  3. H

    "No (non-missing) observations" error in jointModelBayes function

    Hi all, I'm trying to fit a joint longitudinal and time-to event model in R as shown here:http://www.r-bloggers.com/joint-models-for-longitudinal-and-survival-data/ Patients were randomized to placebo or treatment ("Treatment_Group"), had a biomarker ("CII") measured at multiple times...
  4. P

    HLM Longitudinal Analysis with 2 Time Points

    Does longitudinal HLM with only two time points differ radically from linear growth curve modeling? I know Raudenbush says you need 3 or more timepoints to test for a linear or other trend but one can still test for change over two time points.
  5. T

    How to statistically analyse this experiment? Also confused about IVs/DVs, pls help!

    Hi, I'm doing a hypothetical test, so if it doesn't make theoretical sense, just ignore please! :D The study is longitudinal one lasting a year in which memory skills of children are assessed with a test quarterly. So at the start, 4 months, 8 months and at the end. The study is...
  6. E

    Examining whether a repeated measure is stable high, or non-stable over time

    Dear all, I have conducted an experiment with a patient versus a control group, in which I asked them to do a reaction time tasks with control words and specific symptom words. The same reaction time task was used on three different days. We want to know whether the patient group shows a bias...
  7. A

    Help with Pre-Post Analyses (only 2 trials and no between subjects effects)

    I need some help for my thesis - am not getting much from my stats committee member. I am looking at change in scores across treatment on a particular measure. I am using data kept in a forensic facility and I don't have any latitude to do more than what they do (i.e., pre and post testing). I...
  8. M

    Methods in longitudinal analyses with different follow-up times

    Hi all, I am new to this forum, but registered because I am looking for the right method to use in the analyses of two different projects, both longitudinal with different follow-up times for patients. I did some research into the study methods, but wasn't sure and wanted to check on this...
  9. F

    Using HLM7 Student for a 3-level diary study

    Hi there, I'm new at using the statistics program HLM7 for Students, and I wonder if someone could help me. I've conducted a longitudinal diary study. It lasted 5 days, in which participants had to fill a different questionnaire three times a day. The questionnaries were different for each...