PARTICIPATING LABORATORIES (235 SURVEYED, 114 RESPONSES) WERE SENT THREE ITEMS: (A) 8 MILLILITERS OF LEADED GASOLINE; (B) A PIECE OF CLOTH CONTAINING 2 MILLILITERS OF THE SAME GASOLINE; AND (C) A SECOND PIECE OF THE SAME CLOTH CONTAINING NO GASOLINE. THE LABORATORIES WERE TOLD ONLY THAT B REPRESENTED EVIDENCE FOUND AT THE SCENE OF AN ATTEMPTED ARSON AND THAT A AND C WERE FROM A VEHICLE OBSERVED FLEEING FROM THE SCENE. THE LABORATORIES WERE TO DETERMINE WHETHER A AND/OR C COULD HAVE A COMMON ORIGIN WITH B, WHETHER THE EVIDENCE DENOTED A CONSPIRACY, AND WHETHER AN ACCELERANT WAS PRESENT, AND TO INDICATE THEIR METHODS OF ANALYSIS. OF THE RESPONDING LABORATORIES, 80 (70.2 PERCENT) CORRECTLY RESPONDED THAT BOTH A AND C COULD HAVE A COMMON ORIGIN WITH B. AN ADDITIONAL 12 RESPONDED THAT C AND B COULD HAVE A COMMON SOURCE BUT WERE INCONCLUSIVE ABOUT A. ALL OF THE LABORATORIES DETERMINED THAT AN ACCELERANT WAS PRESENT. THE RESEARCHERS DECIDED NOT TO REPORT RESPONSES TO THE QUESTION ABOUT CONSPIRACY. DETAILS OF THE FINDINGS AND METHODS OF BOTH REFEREE AND TEST LABORATORIES ARE PRESENTED IN SIX TABLES, INCLUDING BREAKDOWNS OF RESPONSES FROM INDIVIDUAL LABORATORIES. AN EXPLANATION OF SURVEY METHODS AND A COPY OF THE QUESTIONNAIRE ARE INCLUDED. OTHER PROFICIENCY TESTS ARE REPORTED IN NCJ 47522-47534 AND 47536-47542. (LKM)