It's a Spanish study, although it was published in English Here is it's abstract:
"The aim of this article was to suggest some changes in the teaching-learning process methodology of the judo osoto-guruma technique, establishing the action sequences and the most frequent technical errors committed when performing them. The study was carried out with the participation of 45 students with no experience regarding the fundamentals of judo (21 men and 24 women; age=24.02±3.98 years old) from the Bachelor of Science of Physical Activity and Sport Science at the University of Vigo. The proceeding consisted of a systematic observation of a video recording registered during the technique execution. Data obtained were analyzed by means of descriptive statistics and sequential analysis of T-Patterns (obtained with THEME v.5. Software), identifying: a) the presence of typical inaccuracies during the technique performance; b) a number of chained errors affecting body balance, the position of the supporting foot, the blocking action and the final action of the arms. Findings allowed to suggest some motor tasks to correct the identified inaccuracies, the proper sequential actions to make the execution more effective and some recommendations for the use of feedback. Moreover, these findings could be useful for other professionals in order to correct the key technical errors and prevent diverse injuries." (...) (From J. Hum. Kinetics 41, 253-263, 2014).
I would encourage people to download the full version though as the abstract does not shed a terrible amount of light on what exactly transpired:
It remains somewhat unclear in how far the study realizes its objectives in that people now would better understand their errors in ô-soto-guruma and could more efficiently address these. When reading the paper what came to mind is an issue is one that our friend Hanon-sensei has often warned for, that at the risk of a possible disjoint one's theoretical/scholarly approach must be matched to an extensive experience on the tatami. What seems to be considered as ô-soto-guruma and is shown on some of the pictures opens the discussion about when ô-soto-guruma is really ô-soto-gari. To fully benefit from scientific-analytical instrumentation, it needs to be used in the right framework. If you use MRI to analyze the anatomy of a cat, the value will be limited if the body of the animal that is inside the MRI is in fact a dog.
Despite these challenges which authors active in this field always have to face the starting point is very valuable. Jûdô techniques are complex, and transfer of skill is very difficult. So the question to better and more objectively analyze errors is valid in order to improve the learning experience of jûdô students and elite competitors.