# Tag Info

### Calculation of degrees of freedom for B-splines

Cubic splines are not just many third-degree polynomials with knots marking the transitions between one polynomial and another, they are constrained third-degree polynomials with knots marking the ...
• 38.7k
Accepted

### Basis dimension (k) too low for the smooth term in a GAMM

It's not a huge problem in your case. The best I can find on it is p.330-331 of this guide by Simon Wood. Because the edf is way below the basis dimension I don't ...
Accepted

### GAMM with Zero-Inflated Negative Binomial - Looking for a package in R

This model is possible with the brms R package which is an interface to R: A slight modification of one of the examples from https://cran.r-project.org/web/packages/brms/vignettes/brms_distreg.html ...
• 47.8k
Accepted

### GAM with many binary factors

You're assuming that the audience here knows quite a lot about your particular subject area and specific task. I'm also going to assume your pseudocode was just a thinko as it is ...
• 47.8k
Accepted

• 2,206
Accepted

### Interpretation help of summary from basic GAM models with random smooths

In my opinion you are correct to be cautious about simply using $p$-values to guide interpretation. {mgcv} has amazing functionality and the significance tests are ...

### Nonparametric version of lme- gamm function in R

I think there is some confusion on the terms and the programming elements, so let me explain a bit what each is: A linear mixed model (LMM) is a linear regression technique that incorporates random ...
• 13.7k
1 vote

### High autocorrelation in GAMM

Does this itsadug-based approach using bam substantially reduce the autocorrelation? ...
• 185
1 vote

### use GAMM models for full circular wind direction data

If the effect of the cyclical component on the response can possibly change smoothly over time, an alternative is to use a smooth modulation model (like the one proposed by Eilers et al. (2008) and ...
• 1,171
1 vote

### use GAMM models for full circular wind direction data

There is nothing per se wrong or flawed about representing wind direction, a circular variable, via a cyclic cubic regression spline. That this approach is not as common (or used at all) in your field ...
• 47.8k
1 vote

### Specifying random effects using GAMM4

Even though these are essentially the same model, you're seeing different behaviour because of how these models are actually fitted. In fit1, the ...
• 47.8k
1 vote
Accepted

### INTERPRETATION OF GRAPHIC RESULTS OF GAM IN R

Q0 If you look closely at the plot for the s(Year) term, you'll see it doesn't actually include 0 everywhere, e.g. the local peak around ~2000. You likely want <...
• 47.8k
1 vote

### How to interpret the plotted difference of in-factor smooths

The first plot showing the two smooths also includes the model constant term (the intercept), whereas the second plot is showing the difference between the two smooths themselves, excluding the ...
• 47.8k
1 vote

### Irregular time series with multiple sampling sites

I would suggest a different strategy, fitting this as a GAM via gam(), and using a count distribution as the real response variable is an integer count. The ...
• 47.8k
1 vote
Accepted

### Does family 'ocat' work with gamm4 in R?

No, ocat doesn't work with gamm4(). From ?family.mgcv As well as the standard families ...
• 47.8k
1 vote

### Getting better p-values for a gam model with multiple explanatory terms using bootstrapping

Although Wood 2006 said that p-values shouldn't be trusted, Wood 2013 said that they should be fine. See help("summary.gam") for the references and ...
• 7,619
1 vote

### GAMM with fragmented spatial data - presence/absence response

You could add s(Year) + s(Year, by = area, m = 1) which will generate a common trend (s(Year)) and ...
• 47.8k
1 vote

### R^2 for mixed effect models (both generalized linear and additive)

You might be interested in checking-out performance's r2() family of functions, that works with mixed models. For gamm4, support should be implemented soon (see ...

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