Exercise

Fitting a trend surface

The acidity data shows pH broadly increasing from north-east to south-west. Fitting a linear model with the coordinates as covariates will interpolate a flat plane through the values.

Instructions

100 XP

The acidity survey data, ca_geo has been pre-defined.

The response, on the left of the ~ sign, is the name of the column we are modeling.
The explanatory variables are on the right of the ~ sign, separated by a + sign, and are the names of the coordinate columns obtained by coordnames().
Fit the model and see if the model parameters are significant by seeing stars in the coefficients table.

Take Hint (-30 XP)