In order to determine replicability of the TW-2 method 110 radiographs were assessed twice. The overall replicability between stages ranged from 82 to 100%, and the greatest variability within the bone was found in the capitate. The mean difference in skeletal ages obtained was 0.11 years. The change in rating criteria from the TW-1 to the TW-2 system towards more well-defined stages, indicates an increase in the precision of the method in terms of a decrease in intra-observer error.
Wenzel, A and Melsen, B
"Replicability of Assessing Radiographs by the Tanner and Whitehouse-2 Method,"
3, Article 13.
Available at: https://digitalcommons.wayne.edu/humbiol/vol54/iss3/13