```r
mod<-gam(data=d, BTVolume~s(Lshell))
summary(mod)
```

```
## 
## Family: gaussian 
## Link function: identity 
## 
## Formula:
## BTVolume ~ s(Lshell)
## 
## Parametric coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  27.8142     0.4557   61.04   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Approximate significance of smooth terms:
##             edf Ref.df     F p-value    
## s(Lshell) 1.493  1.847 198.8  <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## R-sq.(adj) =   0.77   Deviance explained = 77.3%
## GCV = 23.993  Scale est. = 23.463    n = 113
```