Acoustics - Measurement of sound insulation in buildings and of building elements - Part 2: Determination, verification and application of precision data (ISO 140-2:1991)

The standard specifies procedures for assessing the uncertainty (repeatability and reproductability values) in the acoustical measurements described in ISO 140-3 to 9 due to random and systematic influences

Akustik - Messung der Schalldämmung in Bauten und von Bauteilen - Teil 2: Angabe von Genauigkeitsanforderungen (ISO 140-2:1991)

Acoustique - Mesurage de l'isolation acoustique des immeubles et des éléments de construction - Partie 2: Détermination, vérification et application des données de fidélité (ISO 140-2:1991)

La présente partie de l'ISO 140 prescrit des méthodes d'évaluation de l'incertitude des mesurages acoustiques décrits dans l'ISO 140-3 à l'ISO 140-9, due aux influences aléatoires et systématiques. Elle donne des directives pour : -- déterminer la valeur de répétabilité r et la valeur de reproductibilité R; -- vérifier les valeurs de répétabilité r et les valeurs de reproductibilité R pour différents dispositifs de mesurage dans un laboratoire et pour des comparaisons entre différents laboratoires; -- appliquer les valeurs de répétabilité r et de reproductibilité R dans la pratique. L'annexe A donne des valeurs provisoires de répétabilité et de reproductibilité des méthodes d'essai conformément à l'ISO 140-3, l'ISO 104-4 et l'ISO 140-6 à l'ISO 140-8.
NOTE 1 On ne dispose actuellement d'aucune donnée pour l'ISO 140-5 et l'ISO 140-9.

Akustika - Merjenje zvočne izolirnosti v zgradbah in zvočne izolirnosti gradbenih elementov - 2. del: Ugotavljanje, preverjanje in uporaba natančnosti podatkov (ISO 140-2:1991)

General Information

Status
Withdrawn
Publication Date
31-Mar-1997
Withdrawal Date
18-Aug-2014
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
19-Aug-2014
Due Date
11-Sep-2014
Completion Date
19-Aug-2014

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Akustik - Messung der Schalldämmung in Bauten und von Bauteilen - Teil 2: Angabe von Genauigkeitsanforderungen (ISO 140-2:1991)Acoustique - Mesurage de l'isolation acoustique des immeubles et des éléments de construction - Partie 2: Détermination, vérification et application des données de fidélité (ISO 140-2:1991)Acoustics - Measurement of sound insulation in buildings and of building elements - Part 2: Determination, verification and application of precision data (ISO 140-2:1991)91.120.20L]RODFLMDAcoustics in building. Sound insulation91.060.01Stavbni elementi na splošnoElements of buildings in general17.140.01Acoustic measurements and noise abatement in generalICS:Ta slovenski standard je istoveten z:EN 20140-2:1993SIST EN 20140-2:1997en01-april-1997SIST EN 20140-2:1997SLOVENSKI

STANDARD
SIST EN 20140-2:1997
SIST EN 20140-2:1997
SIST EN 20140-2:1997

INTERNATIONAL STANDARD ISO 140-2 Second edi tion 199 1-06-15 Acoustics - Measurement of Sound insulation in buildings and of building ekments - Part 2: Determination, verification and application of precision data Acoustique - Mesurage de l’isolation acoustique des immeubles et des Wments de construction - Partie 2: Determination, vtkification et application des donnees de fid@lit@ -. -- ---- _p--.--------------- Reference number ISO 140-2: 199 1 (E) SIST EN 20140-2:1997

ISO 140=2:1991(E) Contents Page 1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..-.................-.. 1 2 Normative references ..,_.........._...... . . . . . . . . . . . . . . . . . . . . . . . ..-.-.....-................ 1 3 Deflnitions . ..“............................................ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4 Determination of the repeatability value r and the reproducibility value R by inter-laboratory tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5 Verification procedure ............... ............................................. ........ 6 6 Application of repeatability values Y and reproducibility values R 6 Annexes A Precision of measurements of Sound insulation in buildings and of building elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..m......e.......................... 8 A.l General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -... .~.“................,..........~.................... 8 A.2 Repeatability values Y for laboratory tests . . . . . . . . . . . . . . . . . . . . . . . . ..-.... 8 A.3 Reproducibility values R for laboratory tests . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 A.4 Field tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..I 8 B Repeatability values Y and reproducibility values R for results expressed in Single-number quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 C Bibliography ................................. ........ ................... ..................... 13 0 ISO 1991 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronie or mechanical, including photocopying and microfilm, without permlssion in writing from the publisher. International Organization for Standardization Case Postale 56 * CH-1211 Geneve 20 l Switzerland Printed in Switzerland ii SIST EN 20140-2:1997

ISO 14002:1991(E) Fareword ISO (the International Organization for Standardization) is a worldwide federation of national Standards bodies (ISO member bodies). The work of preparing international Standards is normally carried out through ISO technical committees. Esch member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Inter- national Standard requires approval by at least 75 % of the member bodies casting a vote. Internationa! Standard ISO 140-2 was prepared by Technical Committee ISO/TC 43, Acoustics. This second edition cancels and replaces the first edition (ISO 14O-2:1978), of which it constitutes a technical revision. ISO 140 consists of the following Parts, under the general title Acoustics - Measurement of sound insuiation in buildings and of build- ing elemen ts: - Part 1: Requirements for laboratories - Part 2: Determination, verification and application of precision data - Part 3: Laboratory building elements --- Part 4: rooms -- Part 5: Field measurem elemen ts and facades -- Part 6: floors measuremen ts of airborne Sound insula tion 0 f Field measurements of airborne Sound insulation between ents of airborne Sound insulation of facade Laboratory measurements of impact Sound insulation of - Part 7: Fjeld measurements of impact Sound insulation of f7oors - Part 8: Laborstory measurements of the reduction impact noise by f7oor coverings on a stan dard floor of transmitted - Part 9: Laboratory measurement of roo m-to-room airbo insulation of a susp ended c eiling with a Plenum ab ove it rne Sound . . . Ill SIST EN 20140-2:1997

ISO 14002:1991(E) - Part 10: Laborstory measurement of airborne Sound insulation of small building elemen ts Annex A forms an integral part of this part of ISO 140. Annexes B and C are for information only. iv SIST EN 20140-2:1997

ISO 140=2:1991(E) Introduction lt is not possible to specify completely the construction of laboratory test facilities or the Sound field conditions obtained. Therefore some details of the test facilities and procedures in ISO 140-3 to ISO 140-9 are left to the choice of the Operator. This, together with the statistical Character of Sound fields within rooms, leads to uncer-tainties in the results due to non-systematic (random) and systematic influences. Random influences tan be determin ed bY rep measure ments under essentially similar mn dit ions. leated independent Systematic influences (for example, size and shape of test rooms, mounting conditions of the test specimen, calibration of measuring equipment) cannot be determined by a simple procedure. Generally, comparison measurements in different test facilities and knowledge of the random uncertainties under these conditions are necessary in Order to assess the systematic influences. In agreement with modern statistical methods, the concepts of repeat- ability and reproducibility obtained from complete test results are used in this part of ISO 140, rather than variances of the individual quantities that make up the test result. Repeatability values and reproducibility values offer a simple means of stating the precision of a test method and sf measurements carried out according 1.o the test method. The repeatability and reproducibility are two extremes, the first measuring the minimum and the second the maximum variability in test results. Other intermediate measures of variability between these two extremes are conceivable, such as repetition of tests within a laboratory over longer time intervals, or by different Operators, or including the ef- fects of recalibration, but these are not considered in this patt of ISO 140. If, in a particular Situation, some intermediate measure should be needed, it must be clearly defined, together with the circumstances un- der which it applies and the method by which it should be determined. V SIST EN 20140-2:1997

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INTERNATIONAL STANDARD ISO 140=2:199l(E) Acoustics - Measurement of Sound insulation in buildings and of building elements - Part 2: Determination, verification and application of precision data 1 Scope This part of ISO 140 specifies procedures for as- sessing the uncertainty in the acoustical measure- ments described in ISO 140-3 to ISO 140-9 due to random and systematic influences. lt gives guidelines for - determination of the repeatability value Y and the reproducibility value R; - verification of repeatability values Y and reproducibility values R for different measure- ment arrangements in one laboratory and for comparisons between different laboratories; - application of repeatability values r and reproducibility values R in practice. Tentative repeatability values and reproducibility values of the test methods according to ISO 140-3, ISO 140-4 and ISO 140-6 to ISO 140-8 are given in annex A. NOTE 1 At present no data are available for ISO 140-5 and ISO 140-9. 2 Normative references The following Standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 140. At the time of publication, the editions indicated were valid. All Standards are subject to revision, and Parties to agreements based on this patt of ISO 140 are encouraged to investigate the possibility of applying the most recent editions of the Standards indicated below. Members of IEC and ISO maintain registers of currently valid lnter- national Standards. ISO 140-3:1978, Acoustics - Measurement of Sound insulation in buildings and of buiiding elements - Part 3: Laborstory measurements of airborne Sound insulation of building elements. ISO 140-4:1978, Acoustics - Measurement of Sound insulation in buildings and of building elements - Part 4: Field measurements of airborne Sound insu- lation between rooms. ISO 140-5:1978, Acoustics - Measurement of Sound insulation in buildings and of building elements - Part 5: Field meascrrements of airborne Sound insu- lation of facade elements and facades. ISO 140-6:1978, Acoustics - Measurement of Sound insulation in buildings and of building elements - Part 6: Laborstory measurements of impact Sound insulation of floors. ISO 140-7:1978, Acoustics - Measurement of Sound insulation in buildings and of building elements - Part 7: Field measurements of impact Sound insu- lation of floors. ISO 140-8:1978, Acoustics - Measurement of Sound insulation in buildings and of buiiding elements - Part 8: Laboratory measurements of the reduction of transmitted impact noise by floor coverings on a Standard floor. ISO 140-9:1985, Acoustics - Measurements of Sound insulation in buildings and of building elements - Part 9: Laboratory measurement of room-to-room airborne Sound insulation of a suspended ceiling with a plenum above it. ISO 717-1:1982, Acoustics - Rating of Sound insu- lation in buildings and of building elements - SIST EN 20140-2:1997

ISO 14002:1991(E) Part 1: Airborne Sound insulation in buildings and of interior buiiding elements. ISO 717-2:1982, Acoustics - Rating of Sound insu- lation in buiidings and of building elements - Part 2: Impact Sound insulation. ISO 717-3:1982, Acoustics - Rating of Sound insu- lation in buildings and of building elemenfs - Part 3: Airborne Sound insulation of facade elements and facades. ISO 5725:1986, Precision of test methods - Determi- nation of repeatability and reproducibility for a stan- dard test method by inter-laboratory tests. 3 Definitions For the purposes of this part of ISO 140, the follow- ing definitions apply. Whenever applicable, they are equivalent to those given in ISO 3534, ISO 5725 and in the International vocabulary of basic and general terms in metrology. 3.1 test result, y: The final value obtained in a sin- gle frequency band by following the complete set of instructions given in a test method. NOTE 2 A set of test resul ts is obtained since a deter- minati on is carri ed out in sever ,al frequency band S. 3.2 true value, u: The value characterizing a quan- tity perfectly defined under the conditions existing when that quantity is considered. For practical pur- poses, it is the arithmetic mean of test results ob- tained by a large number of laboratories. Consequently, such a practical true value is associ- ated with the particular test method. 3.3 accuracy of the mean: The closeness of agree- ment between the true value and the mean result obtained by applying the test method a very large number of times. The smaller the systematic part of the experimental errors affecting the results, the more accurate is the test method. 3.4 precision: The closeness of agreement be- tween mutually independent test results obtained under prescribed conditions. NOTES 3 Precision depends only on the distribution of random errors and does not relate to the true value or the speci- fied value. 4 Repeatability and reproducibility are concepts of pre- cision. See ISO 5725. 3.5 arithmetic mean, j? The arithmetic mean of test results, given by the equation where n is the number of test results yi. 3.6 Sample variance, s*: The sum of squares of the deviations from the arithmetic mean of test results, divided by the number of degrees of freedom. In the simple case of n consecu tive (ungroup ed) test re- sults, t he sampl e variance is gi ven by th ee quation (2) 3.7 Standard deviation, s: The Square root of the Sample variance. 3.8 number of degrees af freedom, v: The number of independent terms contained in the expression for the Sample variance. In the simple case of II consecutive (ungrouped) test results V=W--l . . . (3) 3.9 repeatability: The closeness of agreement be- tween mutually independent test results obtained under repeatability conditions. NOTE 5 Repeatability tan depend on the type of con- struction (homogeneity, resonance, etc.). 3.10 repeatabiiity conditions: Conditions where mutually independent test results are obtained with the Same method on identical test material in the Same laboratory with the Same equipment by the Same Operator within short intervals of time. 3.11 repeatability Standard deviation, s,: The stan- dard deviation of test results obtained under re- peatability conditions. lt is a Parameter of dispersion of the distribution of test results under repeatability conditions. NOTE 6 Similarly, the repeatability variance and re- peatability coefficient of Variation could be defined and used as Parameters of dispersion of test results under repeatability condi tions. 3.12 repeatability value, r: The value below which the absolute differente between two Single test re- sults obtained under repeatability conditions may be expected to lie with a probability of 95 %. 3.13 reproducibility: The closeness of agreement between test results obtained under reproducibility conditions. NOTE 7 Reproducibility tan depend on the type of con- struction (homogeneity, resonance, etc.). 2 SIST EN 20140-2:1997

ISO 140=2:1991(E) . . . (4) 3.14 reproducibility conditions: Conditions where test results arc obtained with the Same method on identical test material in different laboratories with different Operators using different equipment. 3.15 reproducibility Standard deviation, +: The Standard deviation of test results obtained under reproducibility conditions. lt is a Parameter of dis- persion of the distribution of test results under reproducibility conditions. NOTE 8 Similarly, the reproducibility variance and reproducibility coefficient of Variation could be defined and used as Parameters of dispersion of test results under reproducibility conditions. 3.16 reproducibility value, R: Value below which the absolute differente between two Single test re- sults obtained under reproducibility conditions may be expected to lie with a probability of 95 %. 3.17 confidence interval (two-sided): An interval between two estimated limits within which a statis- tical Parameter is expected to be found with a prob- ability of 95 %. 3.18 critical differente, Cr&: In statistical termi- nology, the repeatability values and the reproducibility values are critical differentes at the 95 % probability level valid for two Single test re- sults obtained under repeatability or reproducibility conditions. NOTE 9 When verifying the repeatability value Y and the reproducibility value R, it is mostly the practice to carry out more than two tests and a critical differente corre- sponding to the average of such tests will be needed. Critical differentes valid under such modified conditions tan be derived from the repeatability value Y and the reproducibility value R and are given in 4.6. 4.7 and clause 5. 4 Determination of the repeatability value r and the reproducibility value R by inter-Iaboratory tests The repeatability value Y and the reproducibility value R of a test method shall be determined by an inter-laboratory test, taking into account the consid- erations given in this clause and using various kinds of test specimens. These determinations should be repeated from time to time, especially whenever changes are made in the test method. 4.1 General The general concept and the procedure for deter- mining the repeatability value 1 Y and reproducibility value R are given in ISO 57 25. The repeatability value Y and the reproducibility value R are given by 7’= , 2BJ 2 s, = 2,84-- . . * (5) where SF is the mean of the within-laboratory vari- ances taken over all participating laborato- ries (weighted according to the number of valid results returned by the participating laboratories; see ISO 5725:1986, 11.6.1); 2 SL is the between-laboratory variance taken over all participating laboratories; 2 SR is the reproducibility variance. The factor 2,8 Comes from the fact that the repeat- ability value I’ and the reproducibility value R apply to differentes between two Single results (see ISO 57253986, 5.5). NOTE 10 The estimators $ and sf are used since true values 0: and c$ are not known. The repeatability value Y and reproducibility value R as determined from equations (4) and (5) are therefore estimatas of these quantities. The repeatability value F and reproducibility value R are determined from the test results of inter- laboratory tests. As many Operators and laborato- ries as possible should participate in such inter-laboratory tests in Order to obtain reliable test results. The proper organization and evaluation of inter-laboratory tests are cotnplicated and require special knowledge of the statistical background. They are dealt with in ISO 5725. In view of the con- siderable expense involved, the instructions given in ISO 5725 shall oe followed in every detail in Order to avoid failure of the test. Additional rules to be observed fot- use in the field of building acoustics are given below. The organization oT an inter-laboratory test involves statistical problems which should be entrusted to a statistical expert. The task of this expert is - to assist in desiqning the inter-laboratory test; - to analyse the data and to eliminate outliers by va rious statistical tests; - to calculate the repeatability values Y and reproducibility values R of the test method from the valid data. When the final repeatability values r and the reproducibility values R have been established by the means of an inter-laboratory test, it is possible to verify that they correspond to a probability of 95 %, as required by the definitions, by means of the data from which they have been computed. While not strictly necessary, this verification may serve as a check for the correctness of the calculations and the quality of the data. The procedures for this are described in 4.6 and 4.7. SIST EN 20140-2:1997

ISO 140=2:1991(E) Since the repeatability values r and the reproducibility values R are calculated from the es- timators .$ and s:, they will themselves be esti- mates, subject to errors. The probability levels associated with the repeatability values r and the reproducibility values R will therefore not be exactly 95 % but only of the Order of 95 %. Nevertheless, differentes larger than the repeatability values I’ or the reproducibility values R shall be considered suspect. 4.2 Test conditions The acoustical test conditions for determining the repeatability value r and reproducibility value R shall correspond to the conditions given in the rele- vant Parts of ISO 140. The test specimen shall not be remounted between repeated measurements. 4.2.1 Esch Iaboratory shall use its normal test pro- cedure when participating in an inter-laboratory test. The criteria which affect the repeatability of the measurement (see the relevant Parts of ISO 140) shall be carefully observed. No deviations from the test procedure laid down shall occur but, carrying out the test by repeating the measurements several times, the Parameters left open in the test procedure shall be represented as well as possible. In par- ticular, the set of microphone positions and Source positions over which averaging is carried out in one measurement shall be selected anew, more or less randomly, for each repeated measurement. NOTE 11 Very strictly defined test procedures tend to improve the repeatability of a specific laboratory but in- crease the possibility of a bias on all test results of that laboratory. Before the inter-laboratory test is started, each par- ticipating laboratory shall report the exact details of its test procedure. 4.2.2 Additional requirements for carrying out inter-laboratory tests for the test specimen Chosen shall be laid down in detail. This refers in particular to the following items: a) quantities to be me rounding numbers; asured and reported, rules for b) number of replicate tests required; c) calibration of test equipment; mounting and sealing condition S of the test specimen, and curing ti me where a ppropria fe. 4.3 Number of participating laboratories Considering the frequency dependence of the quan- tities measured in building acoustics (comparable to the “level of the test property” of ISO 5725:1986, 5.2), the number of laboratories should, from a statistical Point of view, be at least p = 8, but it is preferable to exceed this number in Order to reduce the number of replicate tests required. The number rz of test re- sults in each laboratory should be so Chosen that ~(n - 1)>35. In addition, at least five test results are needed for each laboratory. The test results ob- tained shall .not be preselected in any way by the participating laboratories before they are reported. 4.4 Requirements for stating the test results of inter-laboratory tests In Order to simplify the evaluation of test results re- ported, it is strongly desirable to supply form- sheet(s) to be filled in by the participants. For the statistical analysis it is important to report special observations and/or any irregularities observed during the tests. 4.5 Choice of test specimen The kind of test specimen to be used for an inter- laboratory test depends not only on the quantity to be tested (i.e. airborne Sound reduction index, nor- malized impact Sound pressure level, etc.) but spe- cifically on the mounting and testing conditions for which the repeatability values and the reproducibility valucs are to be obtained (e.g. Walls, floors, windows). The effect of ageing on the test specimen shall be also be considered. The choice of test specimen also depends on prac- tical considerations and influences the course of action to be taken in case of failure of the inter- laboratory test. Generally speaking, three different Plans depending on the type of test method and/or on the type of specimen rnay be appropriate (see 4.5.1 to 4.5.3). 4.5.1 Use of a Single test specimen (Same material circulated among participants) For checking the test procedure and the test facili- ties in different laboratories, ideally, the Same test specimen should be used by all participants in the inter-laboratory test and checked again by the fit-st laboratory at the end of the inter-laboratory test. In building acoustics, this procedure will often not be feasible due to the long period of time required, the risk of darnage or Change of the test specimen, and different sizes of test openings. However, the variability resulting from the use of more than one test specimen is avoided and the reproducibility values R thus obtained are characteristic for the test facility and test procedure alone. 4 SIST EN 20140-2:1997

ISO 14002:1991(E) 4.52 Use of several test specimens taken from a production lot (nominally identical material exchangeable among participants) In contrast to the procedure described in 4.5.1, all participants of the inter-laboratory test receive nominally identical test specimens, i.e. coming from the Same production !ot or of identical design and constructed by one manufacturer. This enables testing in parallel and reduces the risk of darnage or of Change due to the influence of time. However, the variability among the test specimens due to their heterogeneity is then inseparable from the error variability of the test procedure, and forms an in- herent part of the reproducibility. For this reason it may be advantageous to check all test specimens for homogeneity with more precision at one labora- tory before the inter-laboratory test and possibly also after its completion. 4.5.3 Use of several test specimens constructed in situ (nominally identical material not exchangeable among participants) When the test specimens cannot be prefabricated and readily transported, they shall be constructed in situ by each participant according to close specifi- cations. In this case the variability among the test specimens due to their heterogeneity is even larger than for test specimens according to 4.5.2. 4.6 Verification of repeatability values Y as part of the inter-laboratory test As stated in 4.3, at least F = 8 Iaboratories should deliver at least II = 5 complete test results. Then, for each frequency band, n(n - 1)/2 absolute differentes between Single resuits y, and y, obtained within the laboratory tan be calculated and compared with the critical differente CrD& IJ+ -y, 1) = Y of that fre- quency band. For all p laboratories and 4 frequen- cies, a total of qpn(n - 1)/2 comparisons will be obtained, and it should be expected that the corre- sponding critical differentes are exceeded in not more than 5 % of the cases. For example, with p=8, n=5 and q= 16 there will be 1280 compar- isons, of which not more than about 64 should ex- ceed the critical differentes. Conversely, the number of times the critical differentes are ex- ceeded divided by the total number of absolute dif- ferences will give the observed probability in the inter-laboratory test which should be at (or near) the 95 % level. 4.7 Verification of reproducibility values R as part of the inter-laboratory test If p= 8 Iaboratories having taken part in an inter- laboratory test had made just one determination each, then p@- 1)/2 absolute differentes between results Y, and J+, of any two laboratories a and b could be compared with the critical differente CrD,,( IV, - y,,)) = R in each frequency band. For q= 16 frequency bands there will be qp(p - 1)/2 = 448 comparisons, and it should be ex- pected that the corresponding critical differentes are exceeded in not more than 5 % of the cases, i.e. not more than about 22 times. Again, the number of times the critical differentes are exceeded divided by the total number of absolute differentes will give the observed probability in the inter-laboratory test, which should be at (or near) the 95 % level. However, as stated in 4.3, at least n = 5 determi- nations should be made by each laboratory and a critical differente corresponding to the average of the test results of each laboratory used. The critical differente for comparing averages is crD,,( l.Fa - Vi I ) = (6) where P- and R have been determined in the inter- laboratory test; & and J, are the averages of na and nb deter- minations made in Iaboratories a and b, respectively. 1 f ‘ja = izb = n, which will usually be the case, then r CrD,,( i.& -Yb 1) =JR2---r2(1-;) . ..(7) For n-- 1, this reduces to the reproducibility value R as expected. The critical differentes thus c:alculated for each fre- quency band are compared wifh the observed dif- ferences of the averages in that frequency band. Since for each laboratory there is one average, the number of possiblte comparisons is the Same as above, namely qpo) -- 1)/2. 4.8 Repeatability walues Y and reproducibility values R Repeatability values r and reproducibility values R obtained from inter-laboratory tests according to 4.1 to 4.5 will be given in the appropriate Parts of ISO 140 when they are revised. For the time being, tentative repeatability values and tentative reproducibility values are listed in table A.l, table A.2 and table A.3. NOTE 12 The repeatability values Y and the reproducibility values R for test results expressed in Single-number quantities are givan in annex B . SIST EN 20140-2:1997

ISO 14092:1991 (E) 5 Verification procedure CrD,,( Iy -yxJ) = -g- x A laboratory x which has not taken part in the inter- laboratory test for determining the repeatability val- ues Y and the reproducibility values R tan verify the proper Operation of its own test procedure using the test results from the inter-laboratory test- It is further recommended that a laboratory verify the proper Operation of its own test procedure from time to time, especially whenever changes in the test procedure itself, the test facility, or the instvu- mentation are made. 5.1 Verification of repeatability values Y By carrying out a series of tests under repeatability conditions, a laboratory tan verify its repeatability values Y using the following procedure. At least 5 complete tests (%>5) comprising 16 fre- quency bands shall be carried out on a test speci- men similar to that used in the inter-laboratory te

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