I would like to see this article more as a starting point than as a final word on the subject. But as JD Dillon says, "The most well-known learning measurement models have been around for decades, and yet the industry continues to struggle with its measurement practices... most learning and development teams still cannot answer critical stakeholder questions." The measurement practices were developed before the age of digital data, writes Dillon, and they have not caught up with modern data strategy (for example, the the five key principles of good data). So what would good learning data look like? This article is, as I say, a good starting point. But as it notes, each learning initiative has to consider this question in its own contenxt, for its own purposes.