Fed Fund Rate vs 30YT since 1970(only cherry picking this year because the data on fred is poor before this period, and end of gold standard is significant) is a perfect 8/8[0].
And how many degrees of freedom went into the choice of metrics to compare? Just because something went 8/8 doesn't mean it will predict the future crashes.
I'd argue that minimum time frame -> maximum time frame is a more fundamental metric than any other individual yield curve.
Which curve am I looking at and for what? The blue line dips a lot of times, but only sometimes does a dip coincide with a recession.
Not the OP, but I'd guess they meant "blue line greater than red line" .
Exactly. When the blue line greater than red line, shortly thereafter a recession occurs. The blue line is set directly by the Fed.