Now Carola Binder

She says: It is difficult to measure the level of "threat" to Federal Reserve independence

An economist making difficulty where none exists.  It is easy to measure the relationship between Congress and the Fed.  The Fed, acting as a currency bankers, necessarily sees the world through the actions of mostly similar member banks.  There is one minimal model of currency banking, that is a printing press, member bankers, and some algorithm. The Fed operates at the short end, it operates from the most recent innovations  (member banks reveal their preferences). And the Fed deals with yield, a ratio.  Your dimensionality is self defined, you will have a top over bottom  and that ratio has to obey your selected algorithm. 

So, as a currency banker, we can measure who the US  Congress is, they have 2.4 trillion on loan, and all the other member banks have 2.4 Trillion on deposit.  And that is your measurement., what is your algorithm?  My algorithm is simple, the Fed wants to keep the queue size of loan request and deposit requests stable.  A very simple model.  So let me apply the measurement to my algorithm:

Here we have deposits and loans at the Fed.  See how much the red wriggles relative to the blue? The two queues are not stable.  There seems too be one great big fat member banks doing all the loan bets and the smaller member banks making the deposit bets







Now  aslk your self, se;lf, what is it what the blue line knows about investment opportunities that the red line is unaware of?.  Why would the US Congress borrow 2.4 T from the Fed for an investment opportunity and none pf the 30 odd member banks could catch one whiff of that opportunity?  Unlikely, what is more likely s that the Fed and Congress are way off track.