Hitachi gives multiple KPI's regarding number of suppliers audited (20), number of non conforming suppliers, number of training plans, number of people attending these and in some cases feedback.
Sources:
"The number of suppliers with whom we have a direct business relationship is approximately 30,000 in 66 countries worldwide (as of March, 2017). Among them, are 10 Hitachi Group companies based in UK."- Point 2
"The results were collected and analyzed to take necessary remedial action. These self-checks have been carried out since fiscal 2007. In 2016, we have asked 316 suppliers to conduct and all of them completed a self-evaluation." - Point 4.3
"Over 185,893 people completed the training using the common e-learning platform" - Point 4.6.1
"The program, consisting of 4 webinars" - Point 4.6.2
"Forty-five people from 32 suppliers based in China attended. We received positive feedback and plan to continue such training in China and other countries." - Point 4.9
"Hitachi, Ltd., have audited its and its subsidiaries’ suppliers in China, Malaysia, and Vietnam from among those providing CSR self-check results. Twenty suppliers were audited in fiscal 2016, and areas noted for improvement were included overtime work exceeding stipulated rules (19 suppliers), failure to conduct periodic inspections of machinery and equipment (6), and insufficient management of hazardous waste (9)" - Point 4.4