WHAT CONTRACTORS SHOULD KNOW ABOUT STATISTICAL SPECIFICATIONS

STATISTICAL SPECIFICATIONS DEFINE THE QUALITY OF THE MATERIALS AND OF THE CONSTRUCTION REQUIRED. PRESENT CONSTRUCTION IS BEING MEASURED IN TERMS OF QUALITY LEVEL, OR AVERAGE QUALITY, AND THE DEVIATION OF QUALITY MEASUREMENT ABOVE AND BELOW THIS AVERAGE. THIS KNOWLEDGE AND THE USE OF STATISTICAL CONCEPTS IN WRITING SPECIFICATIONS WILL TAKE INTO ACCOUNT THESE FOUR IMPORTANT FACTS' /1/ VARIATIONS EXIST IN WHATEVER PROPERTY MEASURED, /2/ IT IS IMPRACTICAL TO TEST ALL OF THE MATERIAL OR ALL OF THE END PRODUCT ON ANY PROJECT, /3/ RANDOM SAMPLING ENABLES DESCRIPTION OF THE PROBABILITY THAT THE PROPERTIES OF THE MATERIALS WHICH HAVE BEEN INCORPORATED ARE WITHIN SOME RANGE, AND /4/ THE MORE NEARLY UNIFORM A PRODUCT IS SPECIFIED, THE MORE THE COST WILL BE. SPECIFICATIONS MUST, THEREFORE, BE DEVELOPED ON A PROBABLISTIC RATHER THAN ON AN ABSOLUTE BASIS. METHODS OF WRITING SPECIFICATIONS BASED ON STATISTICAL PARAMETERS ARE REVIEWED. DEFINITIVE TESTING AND BETTER QUALITY DEFINITION OF MATERIALS AND CONSTRUCTION ARE NEEDED. THE CONCEPTS AND METHODS PRESENTED WILL IMPROVE CONSTRUCTION QUALITY AND, BECAUSE OF THE ELIMINATION OF UNCERTAINTIES IN BIDDING, WILL EVENTUALLY LOWER THE COST.

• Supplemental Notes:
  • Vol 116, No 4, PP 74-75, 78, 98, 2 PHOT
• Publication Date: 1967-4

Media Info

• Serial:
  • Roads and Streets
  • Publisher: Donnelley (Reuben H) Corporation

Subject/Index Terms

• TRT Terms: Building materials; Construction; Economics; Probability theory; Quality control; Randomization; Sampling; Specifications; Statistical analysis
• Uncontrolled Terms: Quality
• Subject Areas: Construction; Data and Information Technology; Economics; Highways;

Filing Info

• Accession Number: 00214726
• Record Type: Publication
• Files: TRIS
• Created Date: Sep 5 1994 12:00AM