For the Three Months Ended March 31,
Year ended
December 31,
2018
2017
Expected term
0.25 – 3.45 years
0.02 – 3.65 years
Expected average volatility
86.14% -346.467
%
108.61% -584.87
Expected dividend yield
-
Risk-free interest rate
1.43% - 2.48
1.53% - 1.98