Dear list members, 
 
I would be very interested in your opinion in the following matter. One = 
frequently reads in econometric papers that certain economic variables = 
(e.g. inflation, GDP, unemployment) are termed "observable" while others = 
(e.g. the NAIRU, potential output, the causal effect of some x on some = 
y) are called "unobservable". I have two questions about this: 
 
1) What do you think is the explanation for this difference/distinction? 
 
Please be as specific as possible (e.g. if you think it is a matter of = 
direct vs indirect measurability, say exactly what that means; similarly = 
if you think it's a matter of measurable vs estimable etc. etc.). 
 
2) What are the loci classici for discussions of the concept of = 
observable IN ECONOMICS? 
 
Again, please be as specific as possible: I am NOT looking at = 
testability, verfifiability, falsifiability etc. but observability. One = 
place is certainly Oskar Morgenstern's On the Accuracy of Economic = 
Observations. Uskali Maki sometimes talks about observables but I think = 
he uses a different concept (according to which variables such as = 
inflation would UNobservable). 
 
Many thanks! 
 
Julian Reiss