X. Liu and Z. Cui, 2011, Approximation Errors of Perturbation Methods in Solving a Class of DSGE Models, Computational Economics, 38(2), 107-128. [Link

On the one hand

It has been shown that the standard numerical method generates quite accurate numerical solution in solving DSGE models with the conventional distributions when policy functions (solutions) do not have kinks. 

On the other hand

The conventional distribution may generate spurious welfare implications. In realizing this, Lucas assumed that the logarithm of exogenous shocks follows a normal distribution with a negative mean: 

In our paper,

Major reference

Schmitt-Grohé, S., and Uribe, M. (2004). Solving Dynamic General Equilibrium Models Using A Second-order Approximation to The Policy Function. Journal of Economic Dynamics and Control, 28, 755–775.