Gunnar Isacsson, "Estimating the Economic Return to Educational Levels
Using Data on Twins", Journal of Applied Econometrics, Vol. 19, No. 1,
2004, pp. 99-119.

The data set used in the paper is taken from the Swedish Twin Registry and
the 1991 wave of the Swedish Level of Living Survey. These data sets are
confidential. Researchers interested in using the data may address their
request to:

Professor Nancy L. Pedersen
The Swedish Twin Registry
Dept of Medical Epidemiology
Karolinska Institutet
Box 281
S-171 77 Stockholm, Sweden
tel: +46-8-728 7418
Fax:: +46-8-31 49 75
E-Mail: Nancy.Pedersen@mep.ki.se

and 

Professor Anders Björklund 
Swedish Institute for Social Research 
Stockholm University
S-106 91 Stockholm
Sweden
E-Mail: anders@sofi.su.se

This directory also contains the files variables.txt, which lists the names
of the variables used in the paper, and estim.sas, which is a SAS program
that was used to produce the estimates in the paper.

Gunnar Isacsson
VTI/TEK
Box 760
781 27 Borlange, Sweden
E-mail:gis@du.se