I have conducted a longitudinal study with four waves of data collection. My data have a nested structure: there are four levels in my data (time - level 1, student - level 2, class - level 3, school - level 4). Student sample size = 51 (no missing values)
I want to fit generalized...
I'd like some general help figuring out which statistical approaches might be useful for my current situation. I'm working with:
A sample of 9 subjects; id
A 'time' variable (measured in seconds [0...~15000]) consisting of about 15,000 observations per subject; time
A continuous dependent...
I have a large dataset with longitudinal data from patients with repeated measures and unbalanced timepoints. The dependent variable is level of protein and I have several fixed predictors. The best fitting model Is a linear mixed model which is a random intercepts and slopes model. The random...
I have a data set which I am trying to find out what is the best way to go about analyzing. I have been asking around and was advised that mixed model is the best way to go.
Basically, this is a brief explaination of my data set.
I am trying to see the efficacy of Drug X on tumor...
In market mix models, my sales(y) depends on 4 promotions(p1--p4). Let (b11, b21, b31, b41 ) be the coefficients of p1--p4 in one iteration and (b12, b22, b32, b42 ) be the coefficients in the second iteration. I check the validity of the model based on some general guidelines:(i)b1--b4 should...
I am a Norwegian phd student exploring the effects of nocturnal road traffic noise exposure in children. One of the research questions is whether noise exposure at different ages (3, 5, 7, 8 years) is associated with body mass index measured at those same four ages (does the association...
I would like some help.
I did a multilevel analysis using GAMM from mgcv package and plot the predict values with the confidence intervals. I read in a few foruns that the plot only use the fixed part from the equation to predict the values used in the plot. Could anyone knows...
I'm trying to analyze the results of my Master Thesis with SPSS.
I've 3 experimental conditions (factor: Group) and for variable A every subject in each condition has 2 expressions (factor: Hemisphere).
I want to test the effects of these 2 factors on my dependent variable A. What I...
I am having a lot of trouble finding any instructions or help with my analysis and was hoping someone here might be able to point me in the right direction.
My experiment involves making a verbal rating at the end of each trial of a visual stimulus. There are two properties of the...
I have a random group of participants that answered questions on a survey regarding their general opinions on specific health activities. Each participant answered questions about 4 randomly selected health activities (Swimming, brushing teeth, etc.).
My dependent variable is days...
I am a wee bit confused about the random statement in PROC MIXED, I thought maybe you can clarify it for me in simple words.
Let's for the illustration say I have an outcome variable Y, and a treatment variable X, getting:
1 - New intervention
0 - Control (or placebo in...
We are planning a randomised clinical trial treating patients with either an active drug or placebo in 20 weeks. We measure the dependent variable several times during the study and want to evaluate the efficacy of the drug at week 20 in respect to placebo. The analysis will be within a...
I have version 21 of spss with advance statistics. I was trying to use the generalized mixed model function, but it's not showing up in my options. I called IBM who agreed I have the correct license to enable this function, but they could not tell me why it's not showing up in my software. Does...
My data is approximately as follows:
400 participants split over 2 interventions. The participants are school students from 14 different schools so we want to use mixed models to allow for this nested data.
The pp's were measured on 4 attitude items both before and after the...
I have been attempting to run the following model in the lme4 package in R.
mod1<-glmer(perc~treatment+region+stage+treatment*stage+region*stage+(tub+aquarium), weights=no start, family=binomial, data=data)
But continue to receive the following error message:
For my bachelor thesis I have to calculate the sum of some betas (betas of x1, x2, and x3) of a linear regression model with fixed effects using SPSS 19 (STATA is only used in master degree). It is the following model:
y = x1 + x2 + ... + x6 + time dummies + fixed bank effects
I have data that looks as follows:
X, y1, y2, y3, y4
0, 54.241, 127.728, 127.73802, 127.73802
31, 65.132, 127.729, 127.73787, 127.73792
59, 65.364, 127.729, 127.73782, 127.73789
Where y1-y4 are just independent...
I've got a basic question about the interface of SPSS linear mixed models.
The initial window provides the option to designate one or more variables as "repeated measures" and to choose a separate covariance structure for these.
I noticed that not using this option doesn't do an...
Been running around in circles with this for a while. I am trying to figure what sort of design I have and how to go about analyzing it. Any help would be great. Details are below.
Sample Date, 3 levels, fixed
Field, 2 levels, assumed to be random from a larger population.
For each sample...
Parts of my question may seem rudimentary but the more I read, the more confused I get so I am going to completely spell out my experiment.
In my study, I have created 4 conditions by crossing 2 factors- 1) comparison type 2) pricing. Each have 2 levels. My questionnaire had...