tu            relationship of trade-union membership to social class (6 levels), number of employees (5 levels), supervisory responsibility (3 levels), age of individual at start of work event, hours worked (3 levels), work with mainly one sex (4 levels) and promotion prospects (2 levels). 
growth        A data frame containing 153 rows and 8 columns. Snijders & Bosker, (1999)
schiz         Severity of Schizophrenia in data from the National Institute of Mental Health (NIMH)
drvisits     German Socio-Economic Panel (SEOP) 
