United States Environmental Protection Agency Environmental Monitoring Systems Laboratory P.O. Box 93478 Las Vegas NV 89193-3478 EPA/60Q/R-92/235 December 1992 Research and Development Strontium in Water Intercomparison Study A Statistical Evaluation of the September 11,1992 Data 6614OHSeNRD.COV-4 ------- Strontium in Water Intercomparison Study September 11, 1992 Environmental Protection Agency Environmental Monitoring Systems Laboratory Las Vegas, Nevada ------- UNITED STATES ENVIRONMENTAL PROTECTION AGENCY OFFICE OF RESEARCH AND DEVELOPMENT ENVIRONMENTAL MONITORING SYSTEMS LABORATORY-LAS VEGAS P.O. BOX 93478 LAS VEGAS, NEVADA 89193-3478 (702/798-2100) Dear Participant, Enclosed are the results of the Nuclear.Radiation Assessment Division (EMSL-LV) Intercomparison Study for Strontium in Water; September 11, 1992. Please take a few minutes to review this report and the analytical data your laboratory submitted to us. If there are any apparent discrepancies, please notify us immediately. We encourage you to make use of the computer-automated data-entry system that has been in place for some time now. As the number of participants increases, and it becomes unrealistic for us to receive results by mail or FAX, the computer system will be our only avenue for accepting data. If you have any questions or comments, please send a message via the data-entry system or contact Frank Novielli at 702/798-2159 or Patricia Honsa at 702/798-2141. Sincerely, rank Novielli Senior Chemist Radioanalysis Branch Enclosure ------- NOTICE This material has been funded wholly by the U.S. Environmental Protection Agency. It has been subject to the Agency's review, and it has been approved for publication as an EPA document. ------- EMSL-LVIntel-comparison Study: Strontium in Water, ll-8ep-1992 1/9 The following pages consist of separate sections for each of the nuclides in this study with four parts per section. After the first, each part is separated from the next by a new page or a thick horizontal bar. The first page of each section is a statistical summary for the nuclide and starts with a statement of the known value, the control limits, and the warning limits. The warning limits are placed at two normalized standard deviations above and below the known value and the control limits are three normalized standard deviations above and below the known value. If you keep control charts, these values will be useful for anticipating problems with the accuracy of your analytical methods. The coin shaped pie chart at the top of the summary page shows the fate of all the samples sent out in number and percentage terms. The pie chart starts at the top and rotates clockwise. The first sector represents those participants who submitted analytical results within both the warning and control limits. The next sector represents those who are in the warning region but not out of control. The third sector represents those who are out of control, but have passed the outlier test. The fourth sector represents those who have failed the outlier test. The last sector represents those participants who have failed to respond properly. This is the case if no analytical results were returned, or less than three determinations were reported, or if the results were received too late. The reeding on the edge of the coin is spaced at one percent intervals, and the sector shading becomes darker as the data reliability decreases. Sectors with zero width are not shown. The table in the center shows a number of statistical quantities calculated from the submitted data based on the mean and median values in relation to the known value, both before and after outlier removal. The lower pie chart uses the same construction as the upper chart and shows the distribution of properly submitted data in terms of deviation from the known value divided into sectors representing one, two, three, and greater than three normalized standard deviations. The second part is an alphabetical listing, in lab-code order, of submitted data and several calculated quantities. An entry that is shaded has been rejected because of one of the reasons listed above or failure of the outlier test. The fifth and sixth columns are a measure of laboratory precision. The Range analysis is a normalized value that you may use to keep precision control charts. If this value is between 2.0 and 3.0, your analytical process precision is in the warning zone; if it exceeds 3.0 it is out of control. The eighth and ninth columns are the differences from the mean of all non-outliers and from the known value, respectively. A tag symbol may appear in the last column. Each page with tags has a symbol definition summary at the bottom. If there is no tag symbol, the data is within the control limits, but it may be in the warning zone. The third part is a three-column listing of result average, tag symbol, and lab-code in average order excluding those labs not responding properly. In this order, all outliers and out-of-control results appear at the top or bottom of the list. The last part is two bar chart displays showing frequency distributions of responding participants. The first chart places the known value at the center and a bar at each 0.2 unit of expected precision. The second chart places the mean of the reported measurements at the center and a bar at each 0.2 unit of standard deviation. In both cases,.a bar includes those results within 0.1 unit up to the maximum of six. Any results more than six units from the center value are shown cumulatively by a shaded bar one past the sixth unit. If the central tendency of the known value distribution folia away from the center, an error in accuracy is indicated. If the distribution is broad, poor precision is indicated. The mean value distribution is similar but uses the average and standard deviation of reported results as its basis. ------- EMSL-LV Intel-comparison Study: Strontium in Water, ll-Sep-1992 2/9 Strontium-89 Statistical Summary 86 Participants The known value of this nuclide is 20.0 pCi/1 with an expected precision of 5.0; the control limits are 11.3 to 28.7; the warning regions are 11.3 to 14.2 and 25.8 to 28.7 20(23.5 %) Failed to respond \ 3(3.5 %) Outliers ' 5(5.9 %) Out of control but not an outlier Statistic 51 (60.0 %) Within all limits Respondents 6(7.1 %) In warning zone but within control Non-outliers Mean Std. Dev. Variance %Coef. ofVar. % deviation of mean from known value Norm. dev. of mean from known value Median % deviation of median from known value Norm. dev. of median from known value 23.68 30.13 907.79 127.23 18.41 0.12 19.00 -5.00 -0.03 Grand Avg 20.04 4.84 23.41 24.15 0.19 0.01 19.00 -5.00 -0.21 8(12.3 %) Mora than 3 norm. S.D. » 6(9.2 %) Between 2 and 3 norm. S.D.' ,37(56.9 %) Within 1 norm. S.D. of known value 14(21.5 %) Between 1 and 2 norm. S.D. ------- 3/9 EM8L-LV Intercomparison Study: Strontium in Water, ll-Sep-1992 Strontium-89 Lab AE AF AK AL AU AW A* BA BO C CA OE- CJ CK CQ CS C3t D DE DG DO DT DZ E EB EH EL FE HK HU 1C J JE JS JY K KX L LM LT M ME MQ MS = 0 = Res. 1 0*0 24.0 20.0 19.0 13.0 15.0 14.0 21.0 22.0 16.0 16.0 19.0 18.0 16.0 238.0 19.0 18.0 21.0 19.0 18.0 31.0 19.0 18.0 16.0 15.0 18.0 19.0 11.0 20.0 20.0 38.0 23.0 24.0 17.0 22.0 21.0 34.0 23.0 30.0 18.0 23.0 Res. 2 0.0 21.0 22.0 21.0 21.0 14.0 - '."' 15.0 24.0 21.0 18.0 - 15.0 19.0 17.0 12.0 22810 18.0 18.0 23.0 20.0 16.0 33.0 21.0 23.0 15.0 18.0 17.0 18.0 12.0 22.0 20.0 27.0 19.0 16.0 15.0 19.0 22.0 34.0 23.0 20.0 19.0 22.0 Res. 3 0,£ 23.0 20.0 20.0 14.0 ' f ',. 15.0 % ' -'. " ' 13.0 21.0 23.0 14.0 f f j f s 17.0 19.0 20.0 14.0 mo 19.0 19.0 18.0 18.0 20.0 33.0 17.0 23.0 16.0 15.0 17.0 18.0 12.0 21.0 22.0 38.0 21.0 22.0 17.0 21.0 21.0 34.0 22.0 26.0 20.0 23.0 No data submitted Insufficient data X S Exper. Sigma 0.00 1.53 1.15 1.00 4.36 ' 0.58 , . . 1.00 1.73 1.00 2.00 1.00 0.00 1.53 2.00 80,61 0.58 0.58 2.52 1.00 2.00 1.15 2.00 2.89 0.58 1.73 0.58 0.58 0.58 1.00 1.15 6.35 2.00 4.16 1.15 1.53 0.58 0.00 0.58 5.03 1.00 0.58 Rng anal (R + SR) 0,000 0.354 0.236 0.236 0.945 ' 0.118 - 0.236 0.354 0.236 0.473 0.236 0.000 0.354 0.473 12.696 0.118 0.118 0.591 0.236 0.473 0.236 0.473 0.591 0.118 0.354 0.118 0.118 0.118 0.236 0.236 1.570 0.473 0.945 0.236 0.354 0.118 0.000 0.118 1.345 0.236 0.118 Normalized deviation Average 0,00 22.67 20.67 20.00 16.00 ; «' 14.67 '> , 14.00 22.00 22.00 16.00 16.00 19.00 18.33 14.00 258.33 18.67 18.33 20.67 19.00 18.00 32.33 19.00 21.33 15.67 16.00 17.33 18.33 11.67 21.00 20.67 34.33 21.00 20.67 16.33 20.67 21.33 34.00 22.67 25.33 19.00 22.67 TAG SYMBOLS Determined to be an outlier (grand-avg) (known) Tag *0J4 0.91 0.22 -0.01 -1.40 -1.86 -2.09 0.68 0.68 -1.40 -1.40 -0.36 -0.59 -2.09 82.55 -0.47 -0.59 0.22 -0.36 -0.71 4.26 -0.36 0.45 -1.51 -1.40 -0.94 -0.59 -2.90 0.33 0.22 4.95 0.33 0.22 -1.28 0.22 0.45 4.84 0.91 1.83 -0.36 0.91 IT s Above U 3 Below -6J3 x 0.92 0.23 0.00 -1.39 * -1.85 * -2.08 0.69 0.69 -1.39 * -1.39 -0.35 -0.58 -2.08 82.56 x -0.46 -0.58 0.23 -0.35 -0.69 4.27 It -0.35 0.46 -1.50 -1.39 -0.92 -0.58 -2.89 0.35 0.23 4.97 IT 0.35 0.23 -1.27 0.23 0.46 * 4.85 It 0.92 1.85 -0.35 0.92 control limit control limit ------- EMSL-LV Intel-comparison Study: Strontium in Water, ll-8ep-1992 4/9 Strontium-89 Lab Res. 1 Res. 2 N - '>*'-': i " '--: t ,f NB 31.0 31.0 NJ 18.0 19.0 NT 23.0 22.0 OA 27.0 24.0 OL-" ' '' PB 20.0 20.0 ^^ f f f ff S ffff ,l?p'~ ' '/,''',,' I*!St ' 7'/' ' ' ' '"" ' /- '"' ' * .. ' .-.-/... ' .-...' ' , W&' , ' ' ,* ' W ', - *,*',-; PV 19.0 17.0 QU 30.0 29.0 QW 27.0 26.0 QZ 22.0 21.0 R 13.0 15.0 nd ', ' "" ' ' RK 18.0 17.0 RM 22.0 19.0 RN 14.0 16.0 fctifeii' ''^3'^Vi; S 17.0 18.0 SC 18.0 18.0 SD 16.0 17.0 SI 16.0 11.0 SS 19.0 20.0 ST 25.0 26.0 i'ttf'' , '- '" t',\ '"' , ' "jtj&%":; 8Z 17.0 17.0 ^ML** ***»'* / *"'" *''**'£' y /f-J$?* § ^ ^s^ ^ ^> "m^^ TO ,, .^l^t? TI 16.0 13.0 TL 24.0 17.0 TM TJP 38*0 40.0 U 17.0 16.0 Average Tag 0.00 x 11.67 s No data submitted 0 s Insufficient data Exper. Rng anal Res. 3 Sigma (R + SR) ' '; ,'" ' ', : ' '' ' 30.0 0.58 0.118 19.0 0.58 0.118 22.0 0.58 0.118 26.0 1.53 0.354 ,/-'' - ,, '- -, . '"' ' ' 20.0 0.00 0.000 f ' '/ " * / ' f f * ' if/*, * /' y''' ' /" ' '''',' " '^ -'.A '"'''', > ,' .' ' '' .,, fc ,;,/, ,// , ,,,/, , .,<- , ,,, ', f ' S s ' s s 20.0 1.53 0.354 30.0 0.58 0.118 28.0 1.00 0.236 20.0 1.00 0.236 15.0 1.15 0.236 , ' 18.0 6.58 0.118 26.0 3.51 0.827 13.0 1.53 0.354 &&- tfi-sL'*. "- ' < - '-. 19.0 1.00 0.236 21.0 1.73 0.354 18.0 1.00 0.236 13.0 2.52 0.591 21.0 1.00 0.236 25.0 0.58 0.118 'SJ&'/<"?^/ ;- '' , '-, ' 17.0 0.00 0.000 s, $fy "f f/fyf'? < f'*f "*, * fstft£ &%f/f'v' * * * ff f' ff ^ f ' f ^^'U?3;5' //''/;-»'' -'- %'/*,'};,,','' 13.0 1.73 0.354 12.0 6.03 1.795 38.0 115 0.236 19.0 1.53 0.354 Data sorted by Laboratory Lab Average Tag 13.33 B^J 14.00 TAG SYMBOLS Normalized deviation Average (grand-avg) (known) Tag '- " '" ', ' ''''*'' 30.67 3.68 3.70 ft 18.67 -0.47 -0.46 22.33 0.80 0.81 25.67 1.95 1.96 '" - * 20.00 -0.01 0.00 f f f _, / > ', * * ' * / ' f * ^ f f 9 * 18.67 -0.47 -0.46 29.67 3.34 3.35 ft 27.00 2.41 2.42 21.00 0.33 0.35 14.33 -1.98 -1.96 * 17.67 -0.82 -0.81 22.33 0.80 0.81 14.33 -1.98 -1.96 * 18.00 -0.71 -0.69 19.00 -0.36 -0.35 17.00 -1.05 -1.04 13.33 -2.32 -2.31 20.00 -0.01 0.00 25.33 1.83 1.85 , , , 17.00 -1.05 -1.04 ' , ' ' ' * f f ' f ,*'"''' , * * 14.00 -2.09 -2.08 17.67 -0.82 -0.81 38.67 0.45 6.47 x 9 17.33 -0.94 -0.92 Average Lab Average Tag Lab SI 14.00 CS TI 14.00 BA ft s Above control limit x = Determined to be an outlier U = Below control limit ------- 5/9 EMSL-LV Intel-comparison Study: Strontium in Water, ll-Sep-1992 Strontium-89 Data sorted by Laboratory Average Average 14.33 14.33 14.67 15.67 16.00 16.00 16.00 16.00 16.33 17.00 17.00 17.33 17.33 17.67 17.67 18.00 18.00 18.33 18.33 Tag Lab RN R AW EH EL CJ CA AL K SZ SD U FE TL RK S DT HK DE Average Tag 18.33 18.67 18.67 18.67 19.00 19.00 19.00 19.00 19.00 20.00 20.00 20.00 20.67 20.67 20.67 20.67 20.67 21.00 21.00 21.00 Lab CQ PV NJ D SC MQ E DO CK ss PB AK KX JY J DG AF QZ JS 1C Average Tag 21.33 21.33 22.00 22.00 22.33 22.33 22.67 22.67 22.67 25.33 25.33 25.67 27.00 29.67 ft 30.67 ft 32.33 ft 34.00 ft 34.33 ft 38.67 x 258.33 x Lab L EB C BO RM NT MS M AE ST ME OA QW QU NB DZ LT JE TP CX % Frequency distribution of responding labs( expected prec. vs known value) n S8 . -6 _ . . . f..l.f II llllll -'4 exp.prec. * ' }aj^m value 1 IT - .. . -T +2 exp. prec. +4 i +« % Frequency distribution of responding labs(std. dev. vs mean value) IU" '----- -6 s No data tn nliii 4 std. dev. -2 mean value submitted TAG SYMBOLS 0 = Insufficient data x s Determined to be an 1 - . ..... +2 std. dev. +4 ft = Above control outlier Jl s Below control i +6 limit limit ------- EMSL-LV Intel-comparison Study: Strontium in Water, ll-Sep-1992 6/9 Strontium-90 Statistical Summary 85 Participants The known value of this nuclide is 15.0 pCi/1 with an expected precision of 5.0; the control limits are 6.3 to 23.7; the warning regions are 6.3 to 9.2 and 20.8 to 23.7 18(21.2 %) Failed to respond -.. 4(4.7 %) Outliers Statistic ; 61 (71.8 %) Within all limits Respondents 2(2.4 %) In warning zone but within control Non-outliers Mean Std. Dev. Variance % Coef. of Var. % deviation of mean from known value Norm. dev. of mean from known value Median % deviation of median from known value Norm. dev. of median from known value 16.92 18.88 356.48 111.59 12.80 0.10 14.33 -4.44 -0.04 Grand Avg 14.50 2.37 5.61 16.34 -3.32 -0.21 14.33 -4.44 -0.28 4(6.0 %) More than 3 norm. S.D. ., 2(3.0 %) Between 2 and 3 norm. S.D. . 5O(74.6 %) Within 1 norm. S.D. of known value 11 (16.4 %) Between 1 and 2 norm. S.D. ------- 7/9 EMSL-LV Intel-comparison Study: Strontium in Water, ll-Sep-1992 8trontium-90 Lab AE AF AK AL AU AW AY BA BO C CA CE CJ CK CQ CS ox D DE DG DO DT DZ E EB EH EL FE HK HU 1C J JE JS JY K KX L LM LT M ME MQ MS = 0 m Res. 1 0# 14.0 15.0 18.0 19.0 18.0 13.0 22.0 14.0 14.0 14.0 14.0 14.0 15.0 12.0 24.0 142.0 14.0 15.0 17.0 14.0 12.0 20.0 15.0 13.0 17.0 15.0 14.0 14.0 10.0 15.0 14.0 10.0 15.0 12.0 15.0 13.0 15.0 18.0 30.0 13.0 14.0 15.0 Res. 2 0.0 15.0 15.0 16.0 15.0 18.0 12.0 20.0 12.0 14.0 13.0 14.0 13.0 14.0 13.0 24.0 SW# 14.0 15.0 14.0 12.0 14.0 20.0 15.0 14.0 16.0 15.0 13.0 14.0 9.0 15.0 16.0 13.0 16.0 12.D 15.0 15.0 14.0 18.0 2&0 15.0 16.0 15.0 Res. 3 0,S 16.0 16.0 16.0 20.0 16.0 13.0 21.0 13.0 14.0 16.0 14.0 12.0 16.0 12.0 21.0 m# 14.0 15.0 16.0 13.0 10.0 20.0 16.0 13.0 16.0 17.0 13.0 14.0 10.0 14.0 15.0 8.0 13.0 13.0 15.0 14.0 14.0 18.0 27*0 14.0 16.0 15.0 No data submitted Insufficient data X s Exper. Sigma 0.00 1.00 0.58 1.15 2.65 ' 1.15 0.58 1.00 1.00 0.00 1.53 0.00 1.00 1.00 0.58 1.73 mai 0.00 0.00 1.53 1.00 2.00 0.00 0.58 0.58 0.58 1.15 0.58 0.00 0.58 0.58 1.00 2.52 1.53 0.58 0.00 1.00 0.58 0.00 1.63 1.00 1.15 0.00 Rnganal (R + SR) o.ooo 0.236 0.118 0.236 0.591 _, 0.236 0.118 0.236 0.236 0.000 0.354 0.000 0.236 0.236 0.118 0.354 11440 0.000 0.000 0.354 0.236 0.473 0.000 0.118 0.118 0.118 0.236 0.118 0.000 0.118 0.118 0.236 0.591 , 0.354 0.118 0.000 0.236 0.118 0.000 0.364 0.236 0.236 0.000 Normalized deviation Average 0,00 15.00 15.33 16.67 18.00 17.33 12.67 21.00 13.00 14.00 14.33 14.00 13.00 15.00 12.33 23.00 166.33 14.00 15.00 15.67 13.00 12.00 20.00 15.33 13.33 16.33 15.67 13.33 14.00 9.67 14.67 15.00 10.33 14.67 12.33 15.00 14.00 14.33 18.00 20.33 14.00 15.33 15.00 TAG SYMBOLS Determined to be an outlier (grand- avg) (known) Tag -5.02 0.17 0.29 0.75 1.21 0.98 -0.64 2.25 -0.52 -0.17 -0.06 -0.17 -0.52 0.17 -0.75 2.94 52.60 -0.17 0.17 0.40 -0.52 -0.87 1.90 0.29 -0.41 0.63 0.40 -0.41 -0.17 -1.68 0.06 0.17 -1.44 0.06 -0.75 0.17 -0.17 -0.06 1.21 4Jfr -0.17 0.29 0.17 IT = Above JJ s Below -6.20 x 0.00 0.12 0.58 1.04 « 0.81 -0.81 2.08 -0.69 -0.35 -0.23 -0.35 -0.69 0.00 -0.92 2.77 52.42 x -0.35 0.00 0.23 -0.69 -1.04 1.73 0.12 -0.58 0.46 0.23 -0.58 -0.35 -1.85 -0.12 0.00 -1.62 -0.12 -0.92 0.00 -0.35 -0.23 1.04 4.62 x -0.35 0.12 0.00 control limit control limit ------- EM8L-LV Intercomparison Study: Strontium in Water, 11.8ep-1992 8/9 8trontium-90 Lab NB NJ NT OA OL PB P0 fE 'P2P pgr PV QU QW QZ R JRC- RK RM RN RE S sc SD SI 88 ST sir sz ijfiA, TB j s. TI TL TM TP TW U Res. 1 13.0 19.0 14.0 15.0 ' 14.0 ' - ' t 19.0 13.0 14.0 13.0 10.0 ., 15.0 11.0 15.0 f ' f 14.0 13.0 12.0 14.0 14.0 9.0 ', ' s fff 16.0 ''"',, ' ' ,'-'' ''i&V,? 'z / " ' *"*' '', , ' ''",-; 14.0 12.0 25*0 15.0 Res. 2 13.0 18.0 14.0 14.0 ff 15.0 , , "r - - , " f f f 21.0 14.0 15.0 12.0 11.0 " 14.0 14.0 14.0 ' / 14.0 14.0 12.0 15.0 15.0 10.0 ;! f * / "f v f'f 16.6 ', , ' '/'? !ft ', , ' < ' if* $ Af" f f j ?' ' ' '$$,'. $,'/,' ' "' ''f''^'' " 12.0 13.0 25.0 14.0 Res. 3 13.0 17.0 14.0 16.0 - '''", 14.0 ''' ''' ' '. ;?-; f f *' ' s ' , " ^ , 12.0 14.0 13.0 12.0 11.0 ' 15.0 13.0 13.0 - 15.0 12.0 12.0 16.0 14.0 11.0 's£,«$;t '{-?'-' 16.0 ''' /?/,*$ &%? ' Exper. Sigma 0.00 1.00 0.00 1.00 - 0.58 " '- .. - ', , 4.73 0.58 1.00 0.58 0.58 ' ,, 0.58 1.53 1.00 - 0.58 1.00 0.00 1.00 0.58 1.00 f f 0.00 ', '':'/''*' ' ',' + , Rng anal (R + SR) 0.000 0.236 0.000 0.236 0.118 - - y * ' 1.120 0.118 0.236 0.118 0.118 * 0.118 0.354 0.236 0.118 0.236 0.000 0.236 0.118 0.236 0.000 f f Normalized deviation Average 13.00 18.00 14.00 15.00 14.33 . ' - 17.33 13.67 14.00 12.33 10.67 - 14.67 12.67 14.00 14.33 13.00 12.00 15.00 14.33 10.00 16.00 " (grand-avg) (known) Tag -0.52 1.21 -0.17 0.17 -0.06 0.98 -0.29 -0.17 -0.75 -1.33 0.06 -0.64 -0.17 -0.06 -0.52 -0.87 0.17 -0.06 -1.56 0.52 ' '^jjijji^Ti,^', \ I-*' - ' '/^s|/'- -;/^y^ v>, '& ''/"'< 15.0 11.0 S'C 16.0 Data Average 0.00 9.67 Tag x Lab B^J ' ''£,?, ''*'' ' ,;/ 1.53 1.00 0.53 1.00 f f f f f 0.354 0.236 0,lt« 0.236 ' ' 13.67 12.00 25,33 15.00 -0.29 -0.87 3,75 0.17 -0.69 1.04 -0.35 0.00 * -0.23 * * * * 0.81 -0.46 -0.35 -0.92 -1.50 * -0.12 -0.81 -0.35 -0.23 -0.69 -1.04 0.00 -0.23 -1.73 0.35 * * -0.46 -1.04 3.58 x 0.00 I^^^HMBMB sorted by Laboratory Average Average s No data submitted 0 = Insufficient data x 10.00 10.33 Tag Lab Average Tag Lab ST JE TAG SYMBOLS = Determined to be an outlier 10.67 12.00 ft s Above U = Below R TL control limit control limit ------- 9/9 Strontium EMSL-LV Intel-comparison Study: Strontium in Water, ll-Sep-1992 -90 Data sorted by Laboratory Average Average 12.00 12.00 12.33 12.33 12.33 12.67 12.67 13.00 13.00 13.00 13.00 13.00 13.33 13.33 13.67 13.67 14.00 14.00 14.00 14.00 Tag Lab SD DT QZ JY CQ RM AY SC NB DO CJ BO FE EB TI QU RN QW NT ME Average Tag 14.00 14.00 14.00 14.00 14.00 14.33 14.33 14.33 14.33 14.33 14.67 14.67 14.67 15.00 15.00 15.00 15.00 15.00 15.00 15.00 Lab KX HK D CE C 88 8 PB L CA RK JS 1C U SI OA MS K J DE Average Tag 15.00 15.00 15.33 15.33 15.33 15.67 15.67 16.00 16.33 16.67 17.33 17.33 18.00 18.00 18.00 20.00 21.00 23.00 25.33 x 28.33 x 166.33 x Lab CK AE MQ E AF EL DG SZ EH AK PV AW NJ LT AL DZ BA CS TP M CX % Frequency distribution of responding labs( expected prec. vs known value) 10- - - - - -6 % 10- - - - - 0 -'* nil v ittii.if ~4 exp. prec. "2 , * Joiown value +2 exp. prec. ** -M +6 Frequency distribution of responding labsCstd. dev. vs mean value) MJU - lllll.fl -4 std.'dev. ;2 ' 6 mean value +2 std.'dev. *'4 s No data submitted TAG SYMBOLS ft = Above control 0 s Insufficient data x s Determined to be an outlier ^ = Below control .;.;.:. +6 limit limit ------- |