Background - Why monitor these statistics?
We all know that the big economic numbers move markets. If GDP comes in - or employment, inflation, any of the big numbers - wildly different from forecast or expected then prices in equity markets will change significantly. Sadly it's rather difficult to gain access to those official numbers before they're released. That bit in Trading Places was a plot device and would be highly illegal in the real world.
So, given that the numbers are important yet privileged access isn't possible we try to devise proxies for them.