The problem? Not many companies have the data to show where they stand one way or the other.

“There’s a lack of information—not because companies are hiding it,” says Elena Philipova, global head of ESG proposition at market data and infrastructure firm Refinitiv. “Companies themselves do not have the data.”

Philipova, who spoke as part of a Fortune virtual event about the power of data and transparency on diversity, equity, and inclusion (DEI), says companies have gotten much better about disclosing the gender composition of their workforce but not other aspects of diversity.

At this point, “investors will take anything just because the starting point is quite low,” she says. And while there currently is no consistent agreement on global standards on DEI disclosures, there is a movement underway to create a common understanding of what companies are expected to measure and report, she says. Refinitiv, for example, has teamed up with Fortune on an initiative called Measure Up, which encourages companies to self-report their racial and ethnic diversity data.

DEI data collection is clearly not just about being able to present metrics to investors. Corey Anthony, senior vice president of human resources and chief diversity and development officer at AT&T, says he needs and uses data just like every other aspect of the business—to identify an objective, develop tactics, and measure how well a leader performs against that plan.

“You cannot do that, or you can’t do it well, if you don’t have good data,” he says.

DEI work is important, Anthony says, “not only because it is the right thing to do, morally and ethically, but also because it’s a business imperative to do it.” Explaining and making that linkage to business outcomes is essential, he says.

Randall Tucker, chief inclusion officer at Mastercard, says that there’s a misconception that DEI “is an HR exercise” rather than a way to think about what perspectives are missing across an entire company.

“Traditionally it was HR people in that capability, but it lends itself to every fact of the organization,” he says, “and I think that’s the path moving forward for all of our organizations.”

Because DEI data is hard to capture, employee self-identification is critical, Tucker says. Mastercard has a campaign to explain to employees that the company is collecting this data “not because we’re trying to be nosy” but because it allows them to put resources into what matters to the employee base. At Mastercard, for example, these efforts have led to initiatives like 16-week gender-neutral parental leave.

Anthony says that at AT&T, the company is very clear about the “value proposition” of self-identification to its employees. The data is always aggregated and must meet a minimum threshold on the number of responses so it remains anonymized.

Companies have to be willing to share the results of data collection even when it’s not flattering, Anthony says. “It’s okay—I don’t know of a single organization or a single industry that can raise their hands and declare victory when it comes to DEI,” he says. Being transparent about that can build trust, he adds.

Philipova says that there is a lot of concern in the investment community around the DEI equivalent of what greenwashing is to climate change. But those who actually walk the walk, she says, will be rewarded.