The phrase "important barometer" means something that indicates or measures the level or state of importance or significance of a particular situation or topic. Full definition
The percentage of sales which go to Amazon is the single most important barometer of a book publishing company's future. (virtualdavis.com)
The energy sector has driven much of the recent capex weakness, and capex is a less important barometer of sentiment in service sectors and asset - lite businesses. (blackrockblog.com)
Many analysts consider spending on basic research to be an especially important barometer of the health of the scientific enterprise. (sciencemag.org)