How do online and RDD phone research compare?

The million dollar ARF Foundations of Quality study conducted in Oct/Nov 2008 involved over 100,000 interviews across 17 different online research panel providers, 1,000 RDD telephone interviews and 1,500 interviews conducted via mail panels. As the ARF continues to release results, the author shares more insight on how online and RDD phone research compare.

How do online and RDD phone research compare?