The klas??? files contain data about two school classes that were part of Andrea 
Knecht's (2008) PhD research data. The information is coded as follows:


klas???-alcohol.dat
====================
3 columns corresponding to the three waves BCD, containing a retrospective measure of 
alcohol consumption of the pupils at the different measurement points. 
 1 = never;
 2 = once;
 3 = 2-4 times;
 4 = 5-10 times;
 5 = more than 10 times;
0(zero) is the code for missing data.


klas???-delinquency.dat
========================
4 columns corresponding to the waves ABCD, containing a scale of minor delinquency
of the pupils at the different measurement points.
 1 = never;
 2 = once;
 3 = 2-4 times;
 4 = 5-10 times;
 5 = more than 10 times;
0(zero) is the code for missing data.


klas???-demographics.dat
=========================
4 columns corresponding to the following 5 variables:
 sex                  1=female, 2=male;
 age                  in years at wave A measurement;
 ethnicity            1=majority (Dutch), 2=minority (non-Dutch);
 religion of father   1=Christian, 2=non-religious, 3=other religion;
0(zero) is the code for missing data for all 4 variables.


klas???-friendship-waveX.dat
=============================
adjacency matrix indicating friendship in wave X (ranging from A through D).
 0 = no friendship;
 1 = friendship;
 9 = incidentally missing nominator;
10 = structurally missing nominator or nominee.


klas???-primary.dat
====================
adjacency matrix indicating friendship in primary school (measured in wave A).
 0 = no friendship or missing data;
 1 = friendship;
 9 = incidentally missing nominator;
10 = structurally missing nominator or nominee.


For class 12p, there additionally are these files:

class12p-dislike-waveX.dat
==========================
adjacency matrix indicating the dislike relation in wave X (ranging from A through D).
 0 = no dislike;
 1 = dislike;
 9 = incidentally missing nominator;
10 = structurally missing nominator or nominee.