Assume that the technology is given by Yt = AtKt where Yt represents output, At is total factor productivity and Kt
is the aggregate capital stock. TFP is driven by a Brownian motion Bt : d At = µ(At)d t +η(At)dBt The law of motion for capital is defined by investment It capital depreciation rate δ and Brownian motion Zt : dKt = (It −δKt)d t +σKt Zt