How to obtain Initial Parameter of Ceramic Impedance data for fitting using Brick Layer Model.

[Sheyi .C. Adediwura]

Hi every one,

I am new to this field and I am having difficulties in guessing the starting values for my experimental data for fitting.

My sample is ceramic with a dominant bulk region as seen in the screenshot attached.

my fitting circuit is this s(p(R1,CPE),p(R2,CPE),R3), from bricklayer model.

p(R1,CPE) = grain interior

p(R2,CPE) = grain boundary 

R3= electrode.

My question is, how do I obtain the starting values for the fitting.

Thanks in anticipation.