Methodology

Generalised Additive Models (GAMs)

Definition

GAM is bla bla

Which link function is used and why

• gaussian
• inverse gaussian
• gamma

Which prediction is used and why

• response
• identity

Robustness test

• R²
• AIC (akaike information criteria)

Universal Kriging (UK)

Definition

UK is bla bla

Semivariogram

What is a semivariogram?

A variogram is a half of the variance sum of the increment that is the regionalized variables Z(x) at the x and x+h.

γ(si,sj) = ½ var(Z(si) - Z(sj))

What does the semivariogram do to Kriging outputs?

• Second order stationarity

What are the existing semvariogram models?

ArcGIS(Geostatistical model) & R(gstat) in common

• Circular
• Spherical
• Gaussian
• Exponential
• Pentaspherical

R gstat only

If you type vgm() in R, you will see a list of semivariogram models that include:

• Matern
• Stein
• Bessel
• Linear
• Periodic
• Wave
• Hole
• Logarithmic
• Power
• Spline

ArcGIS only

• Tetraspherical

• Rational Quadratic

• Hole Effect

• K-Bessel

• J-Bessel

• Stable

Why I used Stein model more frequently

Applying road:non-road ratio

Final results

Validation