In theory, organizations with ~2x the budget should produce about ~2x the output. There are, of course, reasons in practice to believe that output does not scale quite so linearly with increases in resources. However, these reasons crucially fall on both sides of our possible expectations, suggesting a linear increase in outputs is a reasonable base expectation.
I’d phrase this section a little differently. I think as a prior you should assume that charities become less cost-effective as they scale. However, the organisations that do grow should be the ones with above-average cost-effectiveness for their size. So even if a charity is less cost-effective than when it was smaller, if funders properly consider size, an average large charity should be equally cost-effective to an average small charity.
I’d phrase this section a little differently. I think as a prior you should assume that charities become less cost-effective as they scale. However, the organisations that do grow should be the ones with above-average cost-effectiveness for their size. So even if a charity is less cost-effective than when it was smaller, if funders properly consider size, an average large charity should be equally cost-effective to an average small charity.