how (adv) — sense 2

Economics is a messy discipline: too fluid to be a science, too rigorous to be an art. Perhaps it is fitting that economists’ most-used metric, gross domestic product (GDP), is a tangle too.[…]But as a foundation for analysis it is highly subjective: it rests on difficult decisions about what counts as a territory, what counts as output and how to value it. Indeed, economists are still tweaking it.