QUESTION: Can I use the Assessor Series database data as evidence for expert witness work?
While we have no way of knowing all the ways our clients use ERI data, we are aware of ERI's data being used by major consulting firms, corporations, government agencies, the Internal Revenue Service, attorneys, and CPA firms. We believe our data is among the best, if not the best, in terms of reliability. Additionally, methodology for many of our products has been developed in cooperation with government agencies (including the IRS for the maximum reasonable compensation analysis tables and comparables reporting design in the Executive Compensation Assessor databases) or out of feedback from customers requesting defensible data.
It is not possible, however, for ERI to warranty any of our data for expert witness testimony as it has been our experience such data is evaluated on a case-by-case basis, and we have no way of knowing what data from our products an expert witness may have compiled.
The following excerpt from the Executive Compensation Assessor methodology (available under the Help menu) provides further information:
ERI Statement as to the Relevance and Reliability of Data
Relevance is totally determinable by the circumstances and situation presented. ERI provides outsourced analyses and presentations of salary, executive compensation, benefit, and cost of living survey data. Reliability is described in a non-exclusive summary:
Theory/Technique Demonstrations
Methodologies accompany each Assessor Series application. These methodologies include definitions of terms, examples of calculations, and identifications of sources and data updates.
Subject to Publication and Peer Review
ERI's peers are its competitors, those firms that also provide data analyses to their clients. Unlike ERI, which solicits an annual subscription, most compensation and benefit consulting firms charge an hourly rate for their research services. ERI data are used by these firms in their consulting with their clients. ERI data and analyzes are under constant review and critique by its competitors. ERI, unlike these firms, provides no fee-for-service/time consulting.
Known or Potential Rate of Error
Each Assessor Series database (with the exception of the Relocation Assessor and Occupational Assessor) illustrates via a Variance Statistics screen (accessed via the 
button in the lower-left corner of the screen) the beginning of a statistical overview of ERI data. Statistics are reported as derived from just one survey source for all salary and compensation presentations (so that copyright restrictions are not violated). ERI accumulates many survey sources to compile its analyses. Hence the data illustrated may be, in ERI's estimate, considered to be the highest possible standard error that might exist with each analysis. Assessor Series application database results are, by logic, more robust than the standard error displayed and reported.
General Level of Acceptance within the Discipline's Community
Thousands of subscribers send money each year to purchase their subscriptions to ERI analyses. Special extracts of ERI databases are purchased annually by large organizations. ERI exhibits at major trade shows (e.g., WaW and SHRM). ERI data is used as source data by major publications and job boards. WorldatWork, NASBA, and HRCI accept ERI Distance Learning Center courses for professional maintenance and recertification continuing education credit. Major U.S. employers rely upon ERI data as cited in corporate proxy filings and court opinions.
The Help files available with our databases also provide extensive information. ERI's methodologies may also be useful to you in answering any specific questions you may have concerning our products.
Also, see 12 Common XA Questions for ERI Expert Witness Voire Dire in the Executive Compensation help.