Thanks for sharing these details. Would love to see your presentation if you can share it on this site.
Legacy data is definitely important, especially to derive meaningful analytics. That’s way, one of the things that I’ve seen to work is a side by side comparison on trends or other analytics derived from past data and how that is with or without including legacy data as part of the data set.
Thank you again for sharing this with us.

George,
I am a geoscientist (in the oil and gas industry), so I spend much of my life attempting to extract value from (existing data) – typically field- or lab-acquired data that becomes “legacy” almost immediately after acquisition. In this context, “legacy data” refers to data liable to decay and to lose fitness-for-purposes (immediate and future, planned and unforeseen). I also spend quite a bit of time planning the acquisition of new data, and I am acutely aware of the pressures to do things faster and cheaper, regardless of value, to the extent that we frequently spend time and money acquiring such half-arsed data sets that they will be of no value.
Data analysts know intimately about the importance of legacy data, although younger people have also been led to believe that technology can make up for any data issue (when in fact technology can make up and cover any data issue, but that doesn’t make it right or confident, only misleading). However, they tend to have little voice and use it even less.
The problem is that decision makers, frequently their +i managers, frequently do not understand about data and are relentlessly bombarded by software manufacturers’ spin. There’s no sexiness in legacy data, when compared to new data… not least because legacy data is imperfect, whereas managers can decree that from now on, all data will be good.
A presentation I gave some years ago to the data management community was entitled “Things are NOT getting better”. I wish they were and advocate for positive changes.

Very true. I’m guessing you had to deal with legacy data quite a bit? In your situation, were the business stakeholders ever convinced on the importance of legacy data?