Chipotle's giveaways may have gained some traction ahead of the embattled chain's Tuesday results announcement.
The restaurant, which had its earnings and stock price battered by an E. coli outbreak, has turned to freebies this year to bring back customers, but company watchers have been split on how much the promotions will help Chipotle recover.
Some 41 percent of Chipotle customers who received a coupon visited the restaurant 3.8 times in the prior 30 days, compared with 1.4 times for the 59 percent of guests who did not receive a promotion, according to a Cowen and Company survey conducted in the first week of April.
Cowen, which has a "market perform" rating on Chipotle with a price target of $430 per share, said the survey leaves it "incrementally positive" on Chipotle's recovery. However, the firm noted that Chipotle's "most loyal customers" may use an "outsized amount" of the coupons, as a recent text promotion showed higher redemption rates than a direct mail effort.
Ells noted during an earnings conference all on Tuesday that same-stores comp sales were up 11 percent since January.
However, Chipotle's free food giveaways failed to revive sales as much as Wall Street expected during the first quarter. Shares in the burrito chain have lost about one-third of their value since food safety woes surfaced with news it had closed dozens of restaurants in the Pacific Northwest due to an E. coli outbreak.
Aggressive marketing efforts by the burrito chain will continue through the summer, the company said. Chipotle is contemplating rewarding consumers based on frequency of purchases and introducing new menu items to entice lapsed customers.
The company tested Chorizo last June and it could possibly join the menu again this year, the company said.
—CNBC's Jacob Pramuk and Reuters contributed to this report.