According to 41 CFR 60-2.12, "jobs at the establishment with similar content, wage rates, and opportunities, must be combined to form job groups. Similarity of content refers to the duties and responsibilities of the job titles which make up the job group. Similarity of opportunities refers to training, transfers, promotions, pay, mobility, and other career enhancement opportunities offered by the jobs within the job group." If there are jobs combined within a job group that should not be, you will not obtain a meaningful result. Once the job groups are properly broken down, if there are not enough for a meaningful analyses, then other tests were used to determine whether any patterns existed showing disparate impact against one group. Within the agency, the number of standard deviations associated with a comparison of the rates for the favored group to the non-favored group when using OFCCP's standard Z test, is a group of 30 or more. As you probably are aware, the larger pools tend to have statistically significant results. The bottom line is every company is different and the analyses should be fitted around the company's practices versus the practices molded to fit a particular analysis. Hope this helps. It's a great question - it can be complicated.