"A local authority much have regard to the desirability of such a formula being simple, objective, measurable, predictable in effect and clearly expressed" (The School Funding (Wales) Regulations 2010, Section 10 paragraph 2)
Did the authority provide a written explanation of the Caerphilly funding formula? Yes. However, it is purely descriptive and features no numbers at all. The only way to assess the formula itself is to analyse the financial data, which Caerphilly also supplied.
Is the formula measurable? Is it predictable? The material supplied by Caerphilly shows the results of the formula rather than how it works. For example, each school gets a lump sum allocation linked to funding managerial tasks for head teachers, building maintenance and some additional funding, but there is no explanation as to how these lump sums are calculated.
The majority of the funding is allocated using pupil teacher ratio calculations. For example, the ratio for Nursery and Reception classes is 25.2:1. However no detail on actual numbers in each year group was provided, and it is not therefore possible to determine how the sums calculated were arrived at.
"The regulations require that 70 per cent of the funding must be distributed on the basis of pupil numbers. (School Funding in Wales Research Briefing August 2018)
Is 70% of school funding based on pupil numbers? Caerphilly's formula is largely based around lump sum allocations and pupil teacher ratios rather than pupil numbers. The lump sum is clearly not based on pupil numbers and a school with over 400 students receives c. 20% more than a school with half that number. However the lump sum forms 5-8% of the total funding for the school, and therefore may not form part of the 70%.
The pupil: teacher ratios vary according to age group, and pupil numbers are also used to determine furniture and equipment budgets, additional support staff and other elements.
It is likely therefore that 70% of the funding is based on some form of pupil calculation. However it is unlikely that Caerphilly can ensure that the funding is "the same funding for pupils of the same age irrespective of the nature of the school which they attend" (The School Funding (Wales) Regulations 2010, Section 23 paragraph 1b).
References: Data Sources for Caerphilly