I make BETI -0.977 as of 2020-11-20, using gox then kraken daily data, with cutoff date of 2013-10-06, and filling in gaps (only a few days in each of gox and kraken) by assuming the price stays the same during the gap.

a: 0.00270185020127701
b: 0.572820201440624
predicted y: 10.7831121120664
predicted price: 48199
ln(todays price): 9.80587472366913
beti: -0.977