The letter "Deprivation not a reason for failure" (TES Cymru, November 12) is factually incorrect. Information on pupil assessment and attainment, including examination performance, was included, as it is in all school reports of this type, within the appendices at the end of the inspection report on Swansea's Dylan Thomas school.
Educational performance is affected by many factors and some of these lie outside, and beyond the control, of the school. However, it is not true to say that school inspectors accept poor educational performance as a result of parental poverty.
When evaluating standards, inspectors working on behalf of Estyn are expected to compare the performance of schools with other similar ones.
Statistics, though, need to be interpreted carefully as they can be misleading.
When considering benchmark information, for instance, we have to recognise that there can be considerable range and variation within benchmark groups.
At the time of the inspection, free school meal entitlement at Dylan Thomas (62 per cent) was 12 percentage points higher than the entitlement of the next highest FSM schools in any part of Wales. Most schools in the benchmark group had FSM figures between 30 and 40 per cent.
So it was reasonable for the inspector to conclude, in this case, that there were no similar schools in Wales with which he could legitimately compare Dylan Thomas.
Even where schools in Wales and England do have similar FSM figures, there are often many other factors that may contribute to significant differences in attainment. These include, for instance, pupil mobility, the number of excluded pupils admitted to the school, the proportion of pupils with additional educational needs, and the level of resources available, as well as increasing differences between the education systems in Wales and England.
Comparisons derived from basic data that do not take account of these broader issues can often be over-simplistic and unsustainable.
We constantly encourage our inspectors to dig deeper into the factors that underlie low attainment. These factors are often of particular significance in schools which, on the face of it, have low levels of attainment compared to apparently similar schools.
Her Majesty's chief inspector of education and training in Wales