1. One reason that many researchers my prefer NOT to use small N designs is that:

They are low in internal validity
Statistical procedures for analyzing the data do not exist
They control the subject’s behavior too much
The external validity of the results may be in question

2. Balancing is a control procedure that:

Distributes the effect of the independent variable equally across all of the treatment conditions
Equates each control subject with a similar experimental one
Distributes the effect of extraneous physical variables equally across the treatment conditions
Simply requires that we conduct one experimental subject for each control subject