> when strictly speaking the raw data has indeed been deleted after being used to create a derivative work that can for all important purposes be used to recreate the original?
To be precise, you almost certainly cannot use this data to recreate anything remotely resembling the original dataset. This type of dimensionality reduction would throw away enormous volumes of data. There is no meaningful sense in which you can reconstruct the data from it.
What they have done is distill some insights about people from this data. It's arguable whether they should be allowed to keep those insights, but there's no privacy risk there really.
It's honestly kind of disingenuous to describe dimensionality reduction in the way that they do here. It is like reducing the resolution of a photo, but it'd best be described as reducing that resolution to say, the 20 most representative pixels. There's no real sense in which the photo still exists.
To be precise, you almost certainly cannot use this data to recreate anything remotely resembling the original dataset. This type of dimensionality reduction would throw away enormous volumes of data. There is no meaningful sense in which you can reconstruct the data from it.
What they have done is distill some insights about people from this data. It's arguable whether they should be allowed to keep those insights, but there's no privacy risk there really.
It's honestly kind of disingenuous to describe dimensionality reduction in the way that they do here. It is like reducing the resolution of a photo, but it'd best be described as reducing that resolution to say, the 20 most representative pixels. There's no real sense in which the photo still exists.