The Company uses the Black-Scholes option pricing model to estimate the grant date fair value of its stock options. There was no income tax benefit recognized in the financial statements for share-based compensation arrangements for the three months ended March 31, 2019 and 2018.

The assumptions underlying the calculation of grant date fair value per share are as follows:

	For the Three Months Ended March 31,
	2019		2018
Number of options granted		74,000		206,500
Volatility	61.35%-61.42%		62.08%
Risk-free interest rate	2.45%-2.50%		2.30-2.64%
Weighted-average expected option term (in years)	6.25		6.08
Dividend yield	—%		—%
Weighted-average fair value per share of grants	0.79		2.14

The stock price volatility for the Company’s options was determined using historical volatilities for industry peers. The risk-free interest rate was derived from U.S. Treasury rates existing on the date of grant for the applicable expected option term. The expected term represents the period of time that options are expected to be outstanding. Because the Company has only very limited historical exercise behavior, it determines the expected life assumption using the simplified method, which is an average of the contractual term of the option and its ordinary vesting period. The expected dividend yield assumption is based on the fact that the Company has never paid, nor has any intention to pay, cash dividends.

On June 19, 2018, the Company’s Shareholders and the Board of Directors approved the Myomo, Inc. 2018 Stock Options and Incentive Plan (the “2018 Plan”). The number of shares of common stock available for awards under the 2018 Plan is equal to 706,119 shares which carries over the remaining 86,119 shares available for grant under the 2016 Plan on April 1, 2018 and increases the share reserve by 620,000 shares, plus on January 1, 2019 and each January 1 thereafter, the number of shares of common stock reserved and available for issuance under the 2018 Plan will be cumulatively increased by 4% of the number shares of common stock outstanding on the immediately preceding December 31 or such lesser number of shares of common stock determined by management in consultation with members of the Board of Directors, including the compensation committee.

Awards of restricted stock units are generally net share settled upon vesting to cover the required employee statutory withholding taxes and the remaining amount is converted into shares based upon their share-value on the date the award vests. These payments of employee withholding taxes are presented in the statements of cash flows as a financing activity.

The Company accounts for stock awards to employees by measuring the cost of services received in exchange for the award of equity instruments based upon the fair value of the award on the date of grant. The fair value of that award is then ratably recognized as expense over the period during which the recipient is required to provide services in exchange for that award.

Options and warrants granted to consultants and other non-employees are recorded at fair value as of the grant date and subsequently adjusted to fair value at the end of each reporting period until such options and warrants vest, and the fair value of such instruments, as adjusted, is expensed over the related vesting period.

The Company attributes the value of stock-based compensation to operations on the straight-line method such that the expense associated with awards is evenly recognized over the vesting period.

The Company recognized stock-based compensation expense related to the issuance of stock option awards to employees and non-employees, restricted stock awards to employees and directors, and restricted stock units to employees, in the statements of operations as follow:

	March 31,
	2019		2018
Research and development	$	27,138	$	31,658
Selling, general and administrative		180,467		304,697

Total	$	207,605	$	336,355

As of March 31, 2019, there was approximately $544,000 of unrecognized compensation cost related to unvested stock options that is expected to be recognized over a weighted-average period of 2.25 years.

As of March 31, 2019, there was approximately $121,000 of unrecognized compensation cost related to unvested restricted stock awards that is expected to be recognized over a weighted-average period of 1.31 years.

As of March 31, 2019, there was approximately $117,000 unrecognized compensation expense related to unvested restricted stock units that is expected to be recognized over a weighted-average period of 1.92 years.