Measurement equation

Hello everybody,
I’m a student and i’m a new dynare user. In paper “Estimating a small open economy DSGE model with indeterminacy: Evidence from China”. As data description, they have:
Output gap : Gap_t = 100ln(Y_t/Ys_t); Y_t : real GDP, Ys_t : potential output.
Inflation rate: Inf_t = 400
ln(P_t/P_t(-1)); P_t : CPI
Nominal Interest Rate : R = CHIBOR (China inter-bank offered rate).
Then they have measurement equations :
Gap_t = y_t
Inf_t = 4pi_t
R = 4
But, in Lubika and Schorfheide (2007): The measurement equations:
output growth : deltaY_t = gammaQ + y_t - y_t(-1) + z_t
Inflation rate : Inf_t = piA + pi_t
Interest rate : Rob_t = piA + rA+ 4*gammaQ + R_t
Both of them have the same data description ( except output gap ). But , they have difference measurement equations.
Any ideas about why? Which measurement equations should i choose ? I have the same data with China case. My english is not good, sorry for any mistake
Thank you in advance for your help.

Please see Pfeifer(2013): “A Guide to Specifying Observation Equations for the Estimation of DSGE Models”
The main difference in your description seems to be whether the model is written down in stationary form and whether the data was demeaned.