Load and pre-process data from relevant CHAMPS database tables

load_data(data_dir)

## Arguments

data_dir Path to directory containing the de-identified L2 data as directly downloaded from CHAMPS (see get_l2_data for information on how to access this data). Data files must not be renamed or modified after downloading.

## Note

The variables in the data are well-documented in the dataset definition PDF file that comes with the L2 data download.