Purchasing managers' indices and their relationship to the economy.
https://www.bis.org/publ/qtrpdf/r_qt1909g.htm
A series of deep declines in European and British Purchasing Managers Indexes (PMIs) are strong evidence of falling economic activity - recessions are probably underway in several cases.
This is a terrible time for so many nations already at grave risk of economic crises to feel they must raise central bank interest rates as rapidly as the Federal Reserve does to prevent the dollar from rising even further (which inflates the cost of imported energy, food and industrial materials for countries with weaker currencies).
A Bank of International Settlements study found PMIs "are reliable concurrent indicators of real activity."
The BIS also noted (ominously) that PMIs are "closely correlated with equity indexes" - falling after stock markets crash.
In the current context of a panicky global stock and bond liquidation after the Fed's recent announcement of surprisingly large and fast interest rate increases, it may prove especially significant that the BIS study also found "it is when the dollar is strong that global PMIs are weak, in spite of any [theoretical] gain in trade competitiveness" for weaker currency countries.