3. Loss per Share

Loss per common share is presented under two formats: basic loss per common share and diluted loss per common share. Basic loss per common share is computed by dividing net loss attributable to common shareholders by the weighted average number of common shares outstanding during the period. Diluted loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding during the period, plus the potentially dilutive impact of common shares equivalents (e.g. stock options and warrants). Dilutive common share equivalents consist of the incremental common shares issuable upon exercise of stock options and warrants. The following table sets forth the computation of basic and diluted net loss per share (in thousands except per share data):


	Year Ended
	December 31, 2019		December 31, 2018
Numerator:
Net loss	$	(12,775)	$	(9,888)

Denominator:
Weighted-average common shares, basic		19,896		18,942
Dilutive effect of stock options		—		—
Dilutive effect of warrants		—		—
Incremental dilutive shares		—		—
Weighted-average common shares, diluted		19,896		18,942
Net loss per share, basic and diluted	$	(0.64)	$	(0.52)

The following outstanding options and warrants were excluded from the computation of basic and diluted net loss per share for the periods presented because including them would have had an anti-dilutive effect (in thousands):


	Year Ended
	December 31, 2019	December 31, 2018
Options to purchase common shares	3,088	2,498
Warrants to purchase common shares	39	—