On Thursday, Equilar released an overview of its findings, without company specifics. Here is an early peek at what to expect as companies start to disclose their official ratios in the coming weeks and months:

Industries

Pay ratios will vary greatly—even dramatically—across broad swaths of the economy, driven in large part by differences in worker pay.

In the energy sector, most CEOs make less than 100 times what their median workers do, partly because the sector generates many high-paying jobs in engineering, on oil rigs and in renewable-energy fields. By contrast, in health care and financial services, where many firms employ large numbers of low-paid workers, CEO pay is typically 150 times that of a company’s median employee.

Expect big swings in median-worker pay figures even within an industry, depending on whether companies choose to exclude international or contract workers when identifying medians. In determining median pay, companies must include part-time, temporary and seasonal workers, but have some leeway in accounting for independent contractors. They may exclude up to 5% of the workforce, but only non-U.S. workers.

MARKET CAP

Bigger companies tend to have bigger pay gaps, the Equilar data suggest. At firms with market capitalizations of less than $700 million, the median CEO pay ratio was 45. In contrast, at companies with $25 billion-plus market values, the pay ratio was around 250.

That disparity is largely a function of CEO pay: Larger companies tend to reward their chief executives with bigger salary, bonus and stock-award packages than smaller firms. Company size, on the other hand, makes less of a difference in pay for the median worker.

Workforce

Companies with larger workforces reported lower median pay for workers—and the highest CEO pay ratios. That is likely because companies with big workforces tend to have more low-wage workers, and their CEOs command bigger paychecks.

Retailers stand out for their low median pay—at just over $13,000, the lowest among the 24 industries in the Equilar survey—and high pay ratio of 669. Chalk it up to the industry’s many part-timers, as well as low hourly wages.

And the larger the workforce, the more likely a company has significant overseas operations, where workers tend to earn less than their U.S. counterparts. For companies with sizable international workforces, that is likely to push up CEO pay ratios.

Region

Where companies are based also helps determine CEO pay ratios. Firms based on the West Coast claimed the highest median pay in the U.S.—and the lowest CEO pay ratio—because of the region’s many high-tech firms and the high cost of living across swaths of California and Washington state.

In the Southeast, where living costs are lower and labor unions have less influence than they do in other manufacturing hubs, median-worker pay was lowest—and pay ratios were highest. "