I considered that, but since we don't have the pre-voucher numbers, how do we know if it increased or not?

It all seem to rest on there being a discontinuity between those that are nearly the same level of income but some get a voucher and some don't but, strangely, the ownership level decreases as you approach the line, then increases again.

The very poorest, with the highest computer ownership, appear to have the highest computer study time too.