Day-to-day precision and batch-to-batch precision

Day-to-day precision and batch-to-batch precision, Total:214 items.

The international standard classification for "Day-to-day precision and batch-to-batch precision" includes: Application of statistical methods , Machine tools , Forging equipment. Presses. Shears , Essential oils , Woodworking machines , Non-ferrous metals in general , Electronic components in general , Boring and milling machines , Advanced ceramics , Non-metalliferous minerals , Rubber compounding ingredients , Machining centres , Tobacco, tobacco products and related equipment , Petroleum products in general .

The Chinese standard classification for "Day-to-day precision and batch-to-batch precision" includes: Mathematics , Gear and thread cutting machine , Metal forming machinery , Fragrances and flavors , Woodworking machine and machine tool , Heavy metal ore , Dedicated processing equipment , Drilling, boring and milling machine , Special ceramics , Metallurgical auxiliary material ore , Carbon black , Machine tool in general , Time and Frequency Measurement , Mechanics Measurement , Tobacco curing in general , Petroleum products in general .

General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China

GB/T 15338-2008 Standard guide for carbon black—Validation of test method precision and bias
GB/T 20957.4-2007 Test conditions for precision machining centres—Part 4:Accuracy and repeatability of positioning of linear and rotary axes
GB/T 29548-2013 High speed precision straight side press—Testing of the accuracy
GB/T 30477-2013 Woodworking Machines - Double Edging Precision Circular Sawing Machines - Nomenclature and Acceptance Conditions
GB/T 27679-2011 Copper,lead,zinc and nickel concentrates—Experimental methods for checking the precision of sampling
GB/T 14455.4-1993 Essential oils. Determination of relative density
GB/T 6379.3-2012 Accuracy(trueness and precision) of measurement methods and results - Part 3：Intermediate measures of the precision of a standard measurement method
GB/T 32553-2016 Fluorspar―Method of determining the precision of sampling and sample preparation
GB/T 9059-1988 Precision gear shaping machines--Testing of the accuracy
GB/T 20957.5-2007 Test conditions of precision machining centres—Part 5: Tests for accuracy and repeatability of positioning of work-holding pallets
GB/T 25995-2010 Test methods for density and apparent porosity of fine ceramics
GB/T 20957.7-2007 Test conditions for precision machining centres—Part 7: Accuracy of a finished test piece
GB/T 29547-2013 Open front high speed precision press—Testing of the accuracy
GB/T 6379.5-2006 Accuracy(trueness and precision) of measurement methods and results -Part 5: Alternative methods for the determination of the precision of a standard measurement method
GB/T 15338-2012 Carbon black - Validation of test method precision and bias
GB/T 15338-1994 Standard guide for carbon black--Validation of test method precision and bias
GB/T 16879-1997 Guidelines for precision and accuracy expression for mask writing equipment
GB/T 30083-2013 Copper, Lead and Zinc Ores and Concentrates - Precision and Bias of Mass Measurement Techniques

Professional Standard - Machinery

JB/T 1579-1999 0
JB/T 8358.2-2006 Precision gear shaping machines -- Testing of the accuracy
JB/T 7177-1993 Fine Blanking Hydraulic Press Precision
JB/T 5569-1991 Precision hobbing machine Precision
JB/T 11770.1-2014 High Speed & Precision CNC Rotary Table - Part 1: Testing of the Accuracy
JB/T 12164.2-2015 CNC ultra-precision micro-surface grinding machine Part 2: Precision inspection
JB/T 8772.4-1998 Test conditions of precision machining centres.Part 4:Accuracy and repeatability
JB/T 8772.5-1998 Test conditions of precision machining centres. Part 5: Tests for accuracy and repeatability of positioning of work-holding pallets
JB/T 8772.7-1998 Test conditions of precision machining centres. Part 7: Accuracy of a finished test piece
JB/T 12290-2015 Straight-side precision press.Testing of accuracy
JB/T 8782-1998 Closed High Speed Precision Press Precision
JB/T 5569-2019 Precise gear hobbing machines-Testing of the accuracy
JB/T 14483.1-2023 Precision flip horizontal machining center Part 1: Accuracy inspection
JB/T 11769.1-2014 Large-sized & Precision CNC Gear Hobbing Machines - Part 1: Testing of the Accuracy
JB/T 13085.1-2017 Precision numerically controlled horizontal turning machines and turning centres-Part 1:Testing of the accuracy

National Metrological Verification Regulations of the People's Republic of China

JJG(邮电) 034-1995 Verification Regulation of Precision Time Interval Meter
JJG 953-2000 Precision Time Interval Meter

Professional Standard - Energy

NB/SH/T 6001-2020 Standard guide for conducting an interlaboratory study todetermine the precision of a test methal

Military Standard of the People's Republic of China-General Armament Department

GJB 2375-1995 Specification for space precision bearing lubricants
GJB 1485-1992 Precision, accuracy and uncertainty of material physical property testing methods

National Metrological Technical Specifications of the People's Republic of China

JJF 1074-2018 Measurement Tables for Density-Concentration of Alcohal
JJF 1259-1990 O.T.N. of the Secondary Standard for the Density(Alcoholometer)
JJF 1074-2001 Measurement Tables for Density - Concentration of Alcohal

Taiwan Provincial Standard of the People's Republic of China

CNS 13959-1997 Method of test for compressive strength of fine ceramics
CNS 13983-1997 Method of test for Vickers hardness of fine ceramics
CNS 6571-1980 Determination of the Density and Relative Density of Essential Oils
CNS 14314-1999 Method of test for particle density of fine ceramic powder
CNS 12703-1990 Method of Test for Flexural Strength (Modulus of Rupture) of High Performance Ceramics at Elevated Temperature
CNS 6571-2006 Essential oils - Determination of relative density at 20 ℃ - Reference method

Professional Standard - Light Industry

QB 974-1984 Determination of Relative Density of Essential Oils

Group Standards of the People's Republic of China

T/CMTBA 1005.1-2019 CNC single column precision vertical lathe——Part 1:Testing of the accuracy
T/CAMMT 40-2022 Digital turning-milling precision forming machine without pattern casting Accuracy test
T/SDMT 0003-2022 Precision CNC Slideways grinding machines - Testing of the accuracy
T/CAMMT 34-2021 Specification for design and development of special die for high strength steel hot stamping forming technology
T/CRSS 0015-2023 Precision and stability testing and evaluation method for Precision planetary reducers

Professional Standard - Aviation

HBJ 15-2005 Rules for Design of Precision Casting Workshop in Aviation Industry

未注明发布机构

ASTM RR-C16-1018 1994 C0302-Interlaboratory Study to Establish Precision Statements for ASTM C302, Test for Density of Performed Pipe-Covering-Type Thermal Insulation
ASTM RR-C09-1033 2003 C1611/C1611M-Interlaboratory Study to Establish Precision Statements for ASTM C1611/C1611M, Standard Test Method for Slump Flow of Self- Consolidating Concrete
DIN EN ISO 4259-1:2020 Petroleum products – Precision of measurement methods and results – Part 1: Determination of precision data of test methods

Jilin Provincial Standard of the People's Republic of China

DB22/T 1522-2011 300~500mm caliber optical element precision grinding machine accuracy

Professional Standard - Tobacco

YC/T 145.2-2012 Tobacco flavor—Determination of relative density
YC/T 145.2-1998 Tobacco flavor. Determination of relative density

工业和信息化部

YD/T 2375-2019 Technical requirements for high accuracy time synchronization

Professional Standard - Post and Telecommunication

YD/T 2375-2011 Technical Requirements for High Accuracy Time Synchronization
YD/T 4504-2023 Technical requirements for interfaces of ultra-high precision timesynchronization

Professional Standard - Forestry

LY/T 1102-1993 Intermittent Wood Vacuum Dryer Accuracy

Professional Standard - Aerospace

QJ 1964-1990 Evaluation Method of Precision and Accuracy of Wind Tunnel Dynamometer Test

国家市场监督管理总局、中国国家标准化管理委员会

GB/T 6683.1-2021 Petroleum and related products—Precision of measurement methods and results—Part 1: Determination of precision data in relation to methods of test

工业和信息化部/国家能源局

JB/T 13546.3-2018 Straight sided single-shaft four-point press of bight speed and ultra precision—Part 3:Testing of the accuracy

SCC

DANSK DS/ISO 5725-3:1995 Accuracy (trueness and precision) of measurement methods and results – Part 3: Intermediate measures of the precision of a standard measurement method
AS B135:1955 Precision levels for engineering workshops
BS 958:1941 Precision levels for engineering workshops
NS 4510:1969 Long solid-stem thermometers for precision use
NS 4511:1969 Short solid-stem thermometers for precision use
AS R34:1969 Long solid-stem thermometers for precision use
AS R33:1969 Short solid-stem thermometers for precision use
BS 1643:1950 Specification for precision vernier height gauges
NS 5655:1980 Test conditions for precision lathes — Testing of accuracy (ISO 1708:1979)
DANSK DS/ISO 5725-5:2000 Accuracy (trueness and precision) of measurement methods and results - Part 5: Alternative methods for the determination of the precision of a standard measurement method
08/30178095 DC BS 6365. Specification for precision vernier depth gauges
NS 4513:1969 Short enclosed-scale thermometers for precision use
NS 4513:1981 Short enclosed-scale thermometers for precision use
08/30178093 DC BS 1643. Specification for precision vernier height gauges
BS 5112-1:1974 Time measurement instruments: chronometers requirements for wrist chronometers with spring balance resonator
NS 4510:1981 Long solid-stem thermometers for precision use
AS 2831:1985 Thermometers - Solid stem - Long and short - For precision use
NS 4511:1981 Short solid-stem thermometers for precision use

British Standards Institution (BSI)

BS ISO 5725-3:1995 Accuracy (trueness and precision) of measurement methods and results. Intermediate measures of the precision of a standard measurement method
BS ISO 5725-3:1994(2002) Accuracy (trueness and precision) of measurement methods and results — Part 3 : Intermediate measures of the precision of a standard measurement method
22/30380920 DC BS ISO 5725-3. Accuracy (trueness and precision) of measurement methods and results - Part 3. Intermediate precision and alternative designs for collaborative studies
BS ISO 5725-3:2023 Accuracy (trueness and precision) of measurement methods and results. Intermediate precision and alternative designs for collaborative studies
BS ISO 14952-6:2003 Space systems. Surface cleanliness of fluid systems - Precision-cleaning processes
BS 1643:1983 Specification for precision vernier height gauges
BS 1643:2008(2009) Speciﬁcation for precision vernier height gauges
BS 1643:2008 Specification for precision vernier height gauges
BS 6365:2008 Specification for precision vernier depth gauges
BS 6365:1983 Specification for precision vernier depth gauges
BS ISO 5725-6:1995 Accuracy (trueness and precision) of measurement methods and results - Use in practice of accuracy values
BS ISO 5725-1:1995 Accuracy (trueness and precision) of measurement methods and results. General principles and definitions
BS ISO 19983:2022 Rubber. Determination of precision of test methods
2SP 68 to 2SP 71-1973 Specification for 100 countersunk precision head aluminium and aluminium alloy rivets
BS 2SP 68 to 2SP 71:1973 Specification for 100 countersunk precision head aluminium and aluminium alloy rivets

VN-TCVN

TCVN 6910-3-2001 Accuracy (Trueness and precision) of measurement methods and results.Part 3: Intermediate measures of the precision of a standard measurement method
TCVN 6910-5-2002 Accuracy (trueness and precision) of measurement methods and results.Part 5: Alternative methods for the determination of the precision of a standard measurement method

Korean Agency for Technology and Standards (KATS)

KS A ISO 5725-3-2022 Accuracy(trueness and precision) of measurement methods and results－Part 3：lntermediate measures of the precision of a standard measurement method
KS A ISO 5725-3-2012(2017) Accuracy(trueness and precision) of measurement methods and results－Part 3：lntermediate measures of the precision of a standard measurement method
KS C 1209-1985 Precision ALTERNATING-CURRENT WATT-HOUR METERS
KS B ISO 1708:2007 General purpose parallel lathes-Testing of the accuracy
KS B ISO 1708:2014 General purpose parallel lathes — Testing of the accuracy
KS B 1427-2009 Accuracy system of injection molded plastic cylindrical gears
KS A ISO 5725-3:2012 Accuracy(trueness and precision) of measurement methods and results－Part 3：lntermediate measures of the precision of a standard measurement method
KS A ISO 5725-5-2022 Accuracy(trueness and precision) of measurement methods and results－Part 5：Alternative methods for the determination of the precision of a standard measurement method
KS A ISO 5725-3-2012(2022) Accuracy(trueness and precision) of measurement methods and results－Part 3：lntermediate measures of the precision of a standard measurement method
KS A ISO 5725-5-2012(2022) Accuracy(trueness and precision) of measurement methods and results－Part 5：Alternative methods for the determination of the precision of a standard measurement method
KS A 3010-1986 Glossary of terms used in instrumentation Accuracy and precision
KS L 1621-2023 Fine ceramics－Test methods for bulk density of fine ceramic powder
KS L 1621-2008 Fine ceramics－Test methods for bulk density of fine ceramic powder
KS H ISO 279-2014(2019) Essential oils — Determination of relative density at 20 degrees C — Reference method
KS H ISO 279-2019 Essential oils — Determination of relative density at 20 degrees C — Reference method

GSO

OS GSO ISO 5725-3:2010 Accuracy (trueness and precision) of measurement methods and results -- Part 3: Intermediate measures of the precision of a standard measurement method
GSO ISO 6152:2010 Thermometers for use with alcoholometers and alcohol hydrometers
OS GSO ISO 5725-5:2010 Accuracy (trueness and precision) of measurement methods and results -- Part 5: Alternative methods for the determination of the precision of a standard measurement method
GSO ISO 4805:2010 Laboratory glassware -- Thermo-alcoholometers and alcohol-thermohydrometers
GSO ISO 14952-6:2015 Space systems -- Surface cleanliness of fluid systems -- Part 6: Precision-cleaning processes
BH GSO ISO 14952-6:2017 Space systems -- Surface cleanliness of fluid systems -- Part 6: Precision-cleaning processes
ISO 19983:2024 Rubber — Determination of precision of test methods
OS GSO ISO 655:2007 Long Enclosed-Scale Thermometers for Precision Use
OS GSO ISO 653:2007 Long Solid-Stem Thermometers for Precision Use

Danish Standards Foundation

DS/ISO 5725-3/Corr.1:2002 Accuracy (trueness and precision) of measurement methods and results - Part 3: Intermediate measures of the precision of a standard measurement method
DS/ISO 5725-5/Corr. 1:2005 Accuracy (trueness and precision) of measurement methods and results - Part 5: Alternative methods for the determination of the precision of a standard measurement method
DS/ISO 5725-5:2000 Accuracy (trueness and precision) of measurement methods and results - Part 5: Alternative methods for the determination of the precision of a standard measurement method

International Organization for Standardization (ISO)

ISO 5725-3:2023 Accuracy (trueness and precision) of measurement methods and results — Part 3: Intermediate precision and alternative designs for collaborative studies
ISO/PRF 5725-3 Accuracy (trueness and precision) of measurement methods and results — Part 3: Intermediate precision and alternative designs for collaborative studies
ISO 5725-3:1994 Accuracy (trueness and precision) of measurement methods and results - Part 3: Intermediate measures of the precision of a standard measurement method
ISO 6152:1982 Thermometers for use with alcoholometers and alcohol hydrometers
ISO 5725-3:1994/cor 1:2001 Accuracy (trueness and precision) of measurement methods and results - Part 3: Intermediate measures of the precision of a standard measurement method; Technical Corrigendum 1
ISO 653:1980 Long solid-stem thermometers for precision use
ISO 654:1980 Short solid-stem thermometers for precision use
ISO 656:1980 Short enclosed-scale thermometers for precision use
ISO 655:1980 Long enclosed-scale thermometers for precision use
ISO/CD 5725-5:2023 Accuracy (trueness and precision) of measurement methods and results — Part 5: Alternative methods for the determination of the precision of a standard measurement method
ISO 4805:1982 Laboratory glassware; Thermo-alcoholometers and alcohol-thermohydrometers
ISO/AWI 5725-5 Accuracy (trueness and precision) of measurement methods and results — Part 5: Alternative methods for the determination of the precision of a standard measurement method
ISO 5725-5:1998 Accuracy (trueness and precision) of measurement methods and results - Part 5: Alternative methods for the determination of the precision of a standard measurement method

German Institute for Standardization

DIN ISO 5725-3:2003 Accuracy (trueness and precision) of measurement methods and results - Part 3: Intermediate measures of the precision of a standard measurement method (ISO 5725-3:1994 including Technical Corrigendum 1:2001)
DIN ISO 5725-3:2003-02 Accuracy (trueness and precision) of measurement methods and results - Part 3: Intermediate measures of the precision of a standard measurement method (ISO 5725-3:1994 including Technical Corrigendum 1:2001)
DIN ISO 5725-5:2002-11 Accuracy (trueness and precision) of measurement methods and results - Part 5: Alternative methods for the determination of the precision of a standard measurement method (ISO 5725-5:1998)
DIN ISO 5725-5 Berichtigung 1:2006 Accuracy (trueness and precision) of measurement methods and results - Part 5: Alternative methods for the determination of the precision of a standard measurement method (ISO 5725-5:1998), Corrigenda to DIN ISO 5725-5:2002-11 (ISO 5725-5:1998/Cor. 1:2005
DIN 2391-1:1994 Seamless precision steel tubes - Part 1: Dimensions

AENOR

UNE 84174:1995 ESSENTIAL OILS. EVALUATION OF THE ABSOLUTE AND RELATIVE DENSITY OF ESSENTIAL OILS. (ELECTRONIC DENSITYMETER METHOD).
UNE 82009-3:1999 ACCURACY (TRUENESS AND PRECISION) OF MEASUREMENT METHODS AND RESULTS. PART 3: INTERMEDIATE MEASURES OF THE PRECISION OF A STANDARD MEASUREMENT METHOD.

RO-ASRO

STAS 12192-1984 G?ARS Choice or precisions and roughness gear
SR 1574-23-1996 Iron ores and concentrates. Determination. of density
STAS 4869-1971 Machine-tools Power hack saws Hequirenicnls for aciiuacy

TR-TSE

TS 768-1969 DETERMINATION OF THE DENSITY AND RELATTVE DENSITY OF ESSENTIAL OILS
TS 2910-1977 IRON ORES - EXPERIMENTAL METHODS FOR CHECKING THE PRECISION OF SAMPLING

IN-BIS

IS 4725-1968 Accuracy requirements for precision gears
IS 5420 Pt.2-1973 Guidelines for Precision of Test Methods Part II Interlaboratory Testing
IS 3636-1966 Precision resistance wire temperature coefficient test method

CU-NC

NC 35-05-1967 Relative density of essential oils

ZA-SANS

SANS 10155:1980 Accuracy in buildings
SANS 5725-3:2009 Accuracy (trueness and precision) of measurement methods and results Part 3: Intermediate measures of the precision of a standard measurement method

American Society for Testing and Materials (ASTM)

ASTM E691-08 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
ASTM E691-99 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
ASTM G117-98 Standard Guide for Calculating and Reporting Measures of Precision Using Data from Interlaboratory Wear or Erosion Tests
ASTM G117-02 Standard Guide for Calculating and Reporting Measures of Precision Using Data from Interlaboratory Wear or Erosion Tests
ASTM G117-02(2007) Standard Guide for Calculating and Reporting Measures of Precision Using Data from Interlaboratory Wear or Erosion Tests
ASTM C729-11 Standard Test Method for Density of Glass by the Sink-Float Comparator
ASTM G117-13 Standard Guide for Calculating and Reporting Measures of Precision Using Data from Interlaboratory Wear or Erosion Tests
ASTM E691-09e1 Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

CZ-CSN

CSN 73 0212-1985 Precision of geometrie parameters in the construction. Precision check
CSN 25 8134-1965 Glass thermometers. Laboratory glass thermometers with fine scale
CSN 56 0210 Cast.3-1981 Testing methods for alcoholic beverages. Determination of density
CSN 28 0130-1956 Accuracy of truck bed with 1435 mm pitch
CSN 44 1822-1989 Iron ores and manganese ores, agglomerates and pellets. Methods for determination of specific, apparent and bulk density

American Society of Mechanical Engineers (ASME)

ASME B40.3-1990 Bimetallic actuated thermometers
ASME B40.3-1997 Bimetallic actuated thermometers
ASME B5.16-1952 Accurary of engine and tool room lathes

PT-IPQ

NP 2993/1-1985 Electronic component. High Precision Rotary Voltage Divider, Midpoint Specifications
NP 74-1956 Rosin essence. associated density
NP 57-1961 Essential oils. Measurement of correlation density
NP 74-1986 Rosin essence. Measurement of correlation density
NP 120-1957 Natural dry essential oil. associated density
NP 2142-1986 Alcoholic beverages. Measurement of concentration and related densities

NO-SN

NS 5655-1980 Test conditions for precision lathes - Testing of accuracy

RU-GOST R

GOST 14618.10-1978 Essential oils, aromatics and their intermediates. Methods for determination of density and refractive index
GOST R 50118-1992 Long enclosed scale termometers for precision use
GOST 30240.5-1995 Barite concentrate. Method for determination of density
GOST R 50117-1992 Short solid-stem termometers for precision use
GOST 19609.18-1989 Concentrated kaolin. Method for determination of density
GOST 26236-1984 Normal and high precision intermediate bushes. Design and dimensions

Defense Logistics Agency

DLA A-A-59119-1997 LAPPING MACHINES, METAL WORKING, HIGH-PRECISION, FLAT SURFACE
DLA A-A-59119 VALID NOTICE 1-2003 LAPPING MACHINES, METAL WORKING, HIGH-PRECISION, FLAT SURFACE

International Telecommunication Union (ITU)

ITU-R OPINION 96-1997 Future Use of the Global Navigation Satellite Ssytem (GNSS) for High-Precision Time Transfer

American National Standards Institute （ANSI)

ANSI/ASTM E691:2013 PRACTICE FOR CONDUCTING AN INTERLABORATORY STUDY TO DETERMINE THE PRECISION OF A TEST METHOD
ANSI/ASME B29.100-2011 Precision Power Transmission, Double-Pitch Power Transmission, and Double-Pitch Conveyor Roller Chains, Attachments and Sprockets
ANSI B5.16-1952 Accuracy of Engine and Tool Room Lathes

CH-SNV

SEV ASE 9002-1960 Yarn and doubling precision. Cotton yarn count

IT-UNI

UNI 4619-1979 Lathe acceptance regulations. Precision ejector lathes with drill heights up to 250mm and drill spacing up to 1500mm

HU-MSZT

MSZ 2270-1988 Class B Precision Slotted Round Nuts
MSZ 2406-1969 Precision support nut. Adjustment length: 1d
MSZ 2410-1969 Precision support nut. Adjustment length: 1d
MSZ 2261-1983 Class A precision cubic short nut
MSZ 2263-1987 Class B precision cubic framed nuts
MSZ KGST 2008-1979 Determination of density and spatiality of glass packaging tools

Lithuanian Standards Office

LST ISO 5725-3+AC1:2007 Accuracy (trueness and precision) of measurement methods and results - Part 3: Intermediate measures of the precision of a standard measurement method (identical ISO 5725-3:1994 including technical corrigendum ISO 5725-3:1994/Cor.1:2001)

ECIA - Electronic Components Industry Association

196-A-1970 Fixed Film Resistors - Precision and Semiprecision

BR-ABNT

ABNT NBR 5992-2016 Fuel ethanol - Determination of the density and alcoholic content by hydrometer
ABNT P-EB-258-1969 High dimensional accuracy rubber seals (O-rings)

Association Francaise de Normalisation

NF T40-005*NF ISO 19983:2017 Rubber - Determination of precision of test methods
NF ISO 279:1999 Essential oils - Determination of relative density at 20 degrees Celsius - Reference method

ESDU - Engineering Sciences Data Unit

ESDU 13003-2016 Modal density of acoustic spaces

Standard Association of Australia （SAA）

AS 4264.4:1996(R2013) Determination of precision and bias in coal and coke sampling

Illuminating Engineering Society of North America

IESNA LM-83-2012 Approved Method: IES Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE)

GM Europe

GME QK 001021-1984 Polyethylen mittlerer Dichte Polyethylene Middle Density German

Society of Motion Picture and Television Engineers (SMPTE)

SMPTE EG 35-1999 Time and Control Code Time Address Clock Precision for Television, Audio and Film

Others: Intra-assay precision and between-assay precision