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Questions tagged [growth-model]

A growth model is a statistical model describing the growth of some population, be it in demographics, biology or otherwise. A well-known example is the logistic growth model.

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18 views

How to test for significant differences between growth curves in repeated measures mixed-models?

I am comparing growth of fish in different habitats and since length and age data is derived from repeated measurements (back-calculations) I am using a mixed model (R, nlme). I have data from ~50 ...
29 views

is LGM without factor variance just comparing means?

Let’s say a simple latent growth model with just two time points, constrained the variance of these two time points to be zero. Are the latent intercept and latent slope then merely using the mean ...
11 views

Can formative measures contribute to latent slope/intercept through a MIMIC model?

I am interested in examining the global trajectory of V over 3 time points (as shown in the figure). Latent V is specified by 4 indicators and 4 predictors/formative indicators. We fixed the ...
54 views

ML method to determine growth of accounts in a bank

Assume a bank has today N checking accounts, and also has 10 years history of the account balances. The history also includes related features such as "Allow overdraft" (Yes/No) and "Opening branch" (...
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Testing for Interaction terms nested models

I have a growth curve model to explore the main factors affecting reading progress. I added gender, income deprivation affecting children index and English as an Additional language as the main ...
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Estimating common slope across two traits for a parallel growth curve model

I am using a parallel growth curve model with 5 waves longitudinal data to evaluate correlated change among 2 traits. For models that showed the effects of correlated change among traits, I'm ...
77 views

Modeling growth curves with different starting sizes (NLME in R)

I am trying to model fish egg growth over time given a starting egg size in R. I have repeated-measures data from individuals with grouping variable "Zafra.1". I do not know when the eggs started ...
21 views

hierarchical linear modeling (HLM)

We are running longitudinal growth curve model in order to predict change over time. Each participant could provide up to 9 measurements (at a variable interval), and we would like to calculate the ...
101 views

How to calculate growth rate from a semi-log plot?

In the following plot, if we model the population growth as a linear function of time, what would be a good estimate of the linear growth rate? I don't know if it's the slope or the intercept!
45 views

How do you choose an appropriate time series regression model?

I am working on a research proposal where I want to test the effect of different macroeconomic variables (i.e. government spending, FDI, trade openness, international GDP growth, etc.) on the GDP ...
39 views

Dealing with different units and indexes in regressions

In my time series model, my dependent variable is a growth measure in percentage. However, one of my independent variables is an index that ranges from -2.5 to 2.5 - and is producing some extreme ...
30 views

What type of transformation for Latent Growth Curve analysis with lavaan when observed variances are over 40,000,000?

Edit: I believe a linear transformation is just fine - divide each number by 100 for example. Just make sure you change back your units when you are interpreting the output! In fact, when I do this, ...
40 views

Change in X Predicts Change in Y

I have a fairly small sample (about 50 individuals) measured at three points in time. At each time point, I measure an outcome (Y) and a possible influence on that outcome (X) along with some ...
34 views

Path analysis of latent variable relationships over time for hypothesis testing

Consider that I have a sample of 30 people (my real data are much bigger), and we ask them how often the would like to eat three types of food (candy, vegetables, and meat) at four points in their ...
29 views

What test to use to compare within-group over time?

I have a set of data of $\approx 13$ people. We collect their data every 2 months for 2 years. I'm interested to see if a variable A in the data affect people's performance as well as their growth ...
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1k views

nls() gradient error in fitting growth curve data

I am trying to model the following data on promotional budget and customer awareness. The idea is, at some point, increase in budget doesn't have any further impact on awareness; it saturates. ...
496 views

How to implement initial GDP variable in time-series growth regression?

I am running a regression on real GDP growth as the dependent variable. I am trying to include an initial year for GDP as an independent variable to control for the initial state of development in a ...
33 views

Longitudinal design: Which method to use if the dependent variable was measured during fewer occasions than the predictors?

I have a longitudinal dataset with 8 repeated measurement occasion and approximately 100 cases. Some of the explanatory variables are time-variant, other stay the same over time. Some might be ...
47 views

How to compare / evaluate parametric growth curves

So I fit a set of (nested) growth models (logistic, gompertz, richards, plus some variants, eg. https://en.wikipedia.org/wiki/Generalised_logistic_function ) to random sub-samples of my data to figure ...
289 views

Latent Change Models: account for change in one latent variable as function of change in another

Hertzog and Dixon (2003) specify that latent change models make it possible to predict change in one latent variable based on change in another. I would appreciate help conceptualizing how to create ...
30 views

No change over time. How to continue analysis?

I would like to conduct a growth curve analysis on longitudinal data. I have read that it is wise to begin with an unconditional means model first, and then move on to random intercepts, and random ...
489 views

Comparing two growth curves (SPSS)

I conducted a study in which students filled out a questionnaire about their motivation at four different times during a semester. Motivation was split up in different types of motivation (as such, ...
33 views

Adjust customer complaints volumes for growth in subscriber base

I have two sets of monthly data that spans over almost 2 years. The subscriber volume, and the customer complaint volume. I'm trying to determine the best way to adjust the changes in complaints ...
195 views

GLM for relative growth rates

I have this experimental design: I have two sets of cell lines. One in which I mutated a gene and another in which I didn't and therefore serves as the control. I grow each of these cell lines under ...
503 views

Are lower-order interactions a prequisite for three-way interactions in regression analysis? [duplicate]

I'm applying growth curve modelling and am interested in modelling a three-way interaction between predictors A x B x C. From what I remember a condition for modelling three-way interactions in ...
296 views

Repeated Measures in SEM

I would have a question about using Structural Equation Modeling for comparing repeated measures results. I have a one DV which has been measured 4 times and corresponds to 4 different experimental ...
379 views

paired t-test as a simple latent change score model

UPDATE: This problem was (embarrassingly) solved by specifying the intercept in the regression equation as shown below: ...
726 views

Change Score Model in lavaan

UPDATE: I think I was over-complicating my problem and am struggling through a new approach as described here: paired t-test as a simple latent change score model I am still accepting the answer ...
3k views

How to normalize and compare growth rates between variables at different stages of some kind of growth model “curve”?

I have a data frame that has various capital and metropolitan cities with various economic, market and performance data. One set of variables is each total annual non-domestic visitor volume and the ...
82 views

How to specify a significance test for intercept and slope between multiple latent groups

I have done a Latent Profile Analysis on 34 symptom-distress-items at beginning of psychotherapy treatment. I came up with 5 latent groups. The entropy of the model was 0.779 The average Latent ...