As an organization, California’s Workers’ Compensation Insurance Rating Bureau (WCIRB) may have the single biggest impact on the (increasing) premium rates California employers pay to insurers.

State leadership looks to the WCIRB for analyses of cost trends, with its reports generally regarded as something like gospel. daisyNews and others have long questioned WCIRB reporting, particularly given the murky provenance of its data, which are supplied entirely by its insurer members and are not verified by the WCIRB itself or any other party.

Now, some members of California’s Commission on Health and Safety and Workers’ Compensation (CHSWC) have begun interrogating the WCIRB’s numbers.

At a recent CHSWC meeting, WCIRB Chief Actuary Tony Milano presented a report on Cumulative Trauma (CT) claims, which lately feature heavily in discussions of comp medical costs. In response to questions from CHSWC Commissioners Jen Hamelin and Shelley Kessler, Milano acknowledged that key aspects of the report were based on surveys of its members on about 400 claims for Accident Years 2022-2024.

The WCIRB has not disclosed the sampling method, the survey questions, or the response rate. Milano explained only that the WCIRB selected its claims “in a statistical way” before asking its members to complete the surveys.

California’s employers, unlike those in most other states, face rising workers’ comp costs. Its comp system continues to spend twice as much to deliver care and benefits as the median states. Too much is at stake to make decisions based on “data” that stakeholders have no visibility into, and are not able to verify as comprehensive or even plausibly representative of long-term statewide trends.

Roughly a decade ago, California legislators mandated comprehensive, system-wide data collection for every claim in the state. Instead, we get…surveys. We salute Commissioners Hamelin and Kessler for posing tough questions, too few of which insurer representatives are asked to face.

“How Many Are In Your Survey?”

The WCIRB and other insurer advocates have made CT claims the hottest topic in comp, with the unmistakable implication that they are driving up costs, and therefore justifying higher premiums.

Moreover, it is impossible to miss the implication that CT claims are somehow invalid.

In the report it presented to CHSWC as well as other reports, the WCIRB suggests a picture of Los Angeles-based law firms spreading a plague of CT claims into Northern California. No data establish a direct causal link between the expansion of LA practices into other regions and the rise in CT claims. Still, the WCIRB and others have consistently discussed the two trends side by side, while stopping short of explicitly questioning the legitimacy of the claims.

Hamelin and Kessler pounced on several misleading aspects of Milano’s presentation, including the WCIRB’s description of CT claims as “litigated” simply because the injured worker was represented by an attorney (whether or not there was any dispute) and its description of “post-termination” CT claims, insinuating without evidence that the workers had been fired before filing their claims.

Finally, Commissioner Hamelin noted Milano’s repeated references to the WCIRB’s “survey” data. As shown below, multiple slides in the WCIRB’s presentation cite “Source: WCIRB claim survey data.”

Hamelin decided to press for answers about this survey data, on which so much of the WCIRB’s argument rested. Their conversation was as follows, with our emphases added:

Hamelin: I just wanted to clarify, when you say you did a survey, is that I.T. speak of how you guys program your surveying, your data, or you actually actively submitted a questionnaire to your membership and X number of people responded?

Milano: It is the latter. So we sample claims, and we did it in a statistical way to get representation across injury types, industries, regions, and then asked our insurer members to fill out the survey per claim.

Commissioner Kessler interjected with a follow-up:

Kessler: How many are in your survey? What are the numbers?

Milano: It’s around 400 in the…It’s 400 total in the survey. Spanning different years and demographics.

That’s it. Surveys of its members on 400-ish claims are the basis of the WCIRB’s current fixation on CT claims, and what appear in our view to be endless insinuations about LA law firms heading North to manufacture revenge claims from disgruntled ex-employees.

The WCIRB’s Black Box

Later during the meeting, daisyBill Cofounder Catherine Montgomery called in to challenge the WCIRB to make its underlying data publicly available, expressing shock at the limited data sets the WCIRB used to push its narratives around CT claims (emphases ours):

“...my ask of the Commissioners is to ask the WCIRB to make the data public that they’re using to put these slides out, and also using to increase premiums for employers in California.”

Milano countered that “on our website, the report does include a lot more information on the data sources, including the survey data.” While the slide deck Milano presented to CHSWC does not include any information about its data beyond the slide footnotes, the WCIRB’s June 2026 CT report, which covers the same ground as its presentation for CHSWC, notes (emphases ours):

“The CT survey data reflects a sample of indemnity claims selected from USR data for which insurers provided additional information and was collected in 2018 for AY 2013–2015 (N = 637) (“prior survey”) and in 2025 for AY 2022–2024 (N = 428) (“current survey”).”

In other words, the only additional details available on the WCIRB’s most recent CT report on its website tell us little more than we already know: the data come from voluntary surveys, with a sample size of about 400 (428, to be precise).

Whose Privacy Is WCIRB Protecting?

Following Montgomery’s statement, Milano claimed that “to the extent we can,” the WCIRB makes “information available to the public.” Seeking clarification, CHSWC Chair Nicholas Roxborough asked if “to the extent we can” referred to privacy issues, to which Milano replied:

“Yeah, releasing the information that’s reported by insurers for, yeah, privacy reasons.”

However, multiple times throughout the presentation, Milano openly stated that the WCIRB has no data on specific injured workers. In response to various questions, Milano reiterated that there was no claimant-specific information to share (emphases ours):

“...we don’t identify who the person is in our data. This is based on survey data.”

“It’s challenging for us to measure that in the data because we don’t identify the individual within our data.”

“...we wouldn’t know who it’s coming from because we don’t know any information about the injured worker.”

The question, then, is whose privacy the WCIRB is protecting by refusing to share its raw underlying data, so that an objective party could verify their validity or challenge the WCIRB’s interpretations of those data.

While 400 or so claims chosen “in a statistical way” are more than anecdotal, they are not an adequate basis from which to draw actionable conclusions about statewide trends over several years. Moreover, given the state’s reliance on WCIRB reporting, stakeholders should have access to its underlying data and methods.

We encourage stakeholders to watch the CHSWC meeting recording and evaluate the WCIRB’s assertions for themselves. The WCIRB is too powerful, and its reports too consequential, for California to continue accepting its conclusions on blind faith.

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