In the 1960s and the 1970s, the pendulum moved toward the social promotion of students. No precise national data record the exact numbers of retained students. However, a number of studies suggest that retention has persisted and possibly has increased. These studies control for the effects of other influencing factors. Poverty, gender, mother's education level, hearing and speech impairments, low birth weight, enuresis, and exposure to household smoking are significant predictive factors.
Research indicates that retention produces negative social implications.
Research also shows that retention may have negative effects on long-term student achievement. Holmes then reviewed only those studies with the greatest statistical control. The negative achievement effects were again demonstrated. These findings were substantively identical to those of Goodlad's analysis in 1954. Subsequent studies have provided little new evidence to contradict Holmes's synthesis of research.