GSA's keyword search matches labor titles, vendor names and contract
numbers. Check population_scope: unrelated titles can enter the pooled
statistics through a matching vendor or contract.

Returns MIXED_SEARCH_FIELDS with no verdict when off-title matches are
detected, or UNVERIFIED_POPULATION with no verdict when the title list
is missing, empty, truncated or approximate. Discover an exact title with
suggest_contains, then use exact_search on labor_category for title-only
rates. Filters match igce_benchmark, including sin and security_clearance.

Returns MIXED_LABOR_TITLES with no verdict when the phrase matches
different grades, specialties or title variants; pooled statistics remain
visible, with the exact-title count when verified. For example, Nurse I
must not be compared as if Nurse II/III/IV rates were the same grade.
Use exact_search with its supported education, experience and business-size
filters to inspect that title. It does not accept SIN or clearance filters;
check those requirements in the returned records and retain paging limits.

A verified exact-title population with at least 20 rates returns z-score,
median comparison, IQR position and delta from average. The z-score is
null when the mean or standard deviation is unavailable or variance is
zero. Missing means produce null average deltas.

A verified exact-title population with fewer than 20 rates returns LOW_SAMPLE
without a high/low verdict;
zero rates return NO_DATA. Statistics compare not-to-exceed ceiling
rates, not prices paid, and do not by themselves establish price
reasonableness or performance risk.