Mae'r cynnwys hwn ar gael yn Saesneg yn unig.
What follows is based upon analysis carried out by researchers at the Wales Institute of Social and Economic Research, Data and Methods (WISERD) over the past few years. This work is continuing and, accordingly, the results reported here should be seen as ‘interim’. However, further results can be made available to the Review; and we should be happy to produce specific analyses for the Review, if asked to do so.