"All but one of the several multi-state studies find a strong link between spending and outcomes –indicating that money matters on average. Importantly, this is true across studies that use different data-sets, examine different time periods, rely on different sources of variation, and employ different statistical techniques. While one can poke holes in each individual study, the robustness of the patterns across a variety of settings is compelling evidence of a real positive causal relationship between increased school spending and student outcomes on average. However, an examination of single-state studies suggests that,on average, money matters, but that this is not always so in all settings or in all contexts."
"All but one of the several multi-state studies find a strong link between spending and outcomes –indicating that money matters on average. Importantly, this is true across studies that use different data-sets, examine different time periods, rely on different sources of variation, and employ different statistical techniques. While one can poke holes in each individual study, the robustness of the patterns across a variety of settings is compelling evidence of a real positive causal relationship between increased school spending and student outcomes on average. However, an examination of single-state studies suggests that,on average, money matters, but that this is not always so in all settings or in all contexts."
Also see "It’s not nothing: The role of money in improving education" (https://www.brookings.edu/research/its-not-nothing-the-role-...) and "How Money Matters for Schools" (https://learningpolicyinstitute.org/product/how-money-matter...).