Workers’ advocates have expressed skepticism about the retailer’s commitment to improving the lives of its more than one million employees. Around the same time that Walmart lifted wages, it cut merit raises and introduced a training program that could keep hourly pay at $9 an hour for up to 18 months.

In November, A Better Balance filed a complaint with the employment commission on behalf of Arleja Stevens, a Walmart employee who said she was fired after missing too many shifts because of complications from her pregnancy.

In that filing, the group accused Walmart of violating the Americans with Disabilities Act and the Pregnancy Discrimination Act. The employment commission is investigating the accusation, Ms. Bakst said.

Mr. Hargrove said the company disagreed with Ms. Stevens’s claims.

A Better Balance also participated in a separate lawsuit last month alleging that Walmart discriminated against pregnant employees

The company has disputed the claims of the two women at the center of the suit.

A Better Balance wrote the survey questions used for Thursday’s report. The questions asked employees whether they believed that Walmart had a problem of regularly punishing people for absences relating to an illness or disability, and about how the company treated absences. The group worked with the labor group OUR Walmart, which promoted the survey to workers who listed Walmart as their employer on Facebook, according to Andrea Dehlendorf, a director of OUR Walmart.

“Although this system is supposed to be ‘neutral’ and punish all absences equally, along the lines of a ‘three-strikes-and-you’re-out’ policy, in reality, such a system is brutally unfair,” the report says of Walmart’s absence-control policy. “It punishes workers for things they cannot control and disproportionately harms the most vulnerable workers.”