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www.online-lims.com. Online QA/QC – Quality Control. Terminology. Precision The term precision is used to describe the reproducibility of results. It can be defined as the agreement between the results of repetitive measurements made in an identical fashion.

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  1. www.online-lims.com Online QA/QC – Quality Control

  2. Terminology Precision The term precision is used to describe the reproducibility of results. It can be defined as the agreement between the results of repetitive measurements made in an identical fashion. Precision can be reported in terms of the deviation (d) of the experimental value from the mean or from the median of a set of data. Keyword: precision -> replicates, duplicates Accuracy The term accuracy is used to denote the nearness of a result to the true or most probable value, and is expressed in terms of error (E).- Keyword: accuracy -> reference material, standards It is essential to understand the fundamental difference between accuracy and precision: “Accuracy involves a comparison with a value accepted as true, while precision is simply a measure of experimental reproducibility.”

  3. Replicate samples Replicates: samples taken at the sample preparation stage. Duplicates: samples duplicated on the worksheet. Used to monitor the precision of a process. Reference samples Standards or reference materials. Blanks (or spikes) Control samples: calibration samples like balance weight, production samples, etc Used to monitor the accuracy of a process. QC Files

  4. ** QC Browser ** • QC browser • QC Charts • Precision control • Accuracy control • Exporting

  5. OnLQC login To change or set the user password switch to the SETUP tab and select <Change Password> User Login Getting Started… The first step in accessing any of the Online LIMS modules is to login the system using your own User ID and password. If you do not have a User ID and password, you will need to get one from the LIMS Administrator. Enter your User ID and password and click OK. If you already log on to the network with a unique User ID and password, that User ID will automatically appear as your LIMS User ID and in most cases your password will be the same as your network password.

  6. OnLQC browser QC Header pane QC file (index) pane QC Test pane The OnLQC browser helps to navigate trough all QC files and to edit QC data. QC files are made up by tree groups: QC Header data, QC Test data and QC Raw data (the only one not accessed by the browser). The browser is divided by tree panes

  7. Browser toolbar - editing Remove test (ROW) Open a QC file for editing Save file after editing Export QC file in Excel Create a new QC file Increment fill down Before creating a new QC ensured that the correct QC TYPE category is selected If GREEN you can edit the QC test. The column header changes from RED to GREEN when the grid is in edit mode

  8. Browser filters Update statistics Filter selection QC Charts QC records can be filtered by the service group that are added on the test pane. One QC file can hold many Service Groups. • This are the principal QC categories and can’t be modified: • Duplicate: replicate statistics • Standard: reference type samples • Blank: Blanks • Control samples, like a balance calibration weight or a routine control sample used in production.

  9. QC Header General purpose note field Where the sample is stored or located Reference material description, precedence Chemist in charge of this file Status and modification audit log Use the QC header to document the reference material.

  10. QC Test Test ID: Must be unique and match with the library, use <Ctrl+Enter> to open the Test pick list Elem: Analysis element. Used exclusively for documentation Unit: Test unit. It has to mach with the LIMS. More units can be added like “ppm,g/ton,mg/L” SGroup: Service group of the test. One QC can hold multiple service groups. Cert Val: Certified value of the reference material Cert Min: Minimum accepted value of the reference material Cert Max: Maximum accepted value of the reference material Count: Data population count. Updated by the system. Can use the “QC Statistic” to update. Notes: General purpose note field.

  11. ** QC Charts ** • QC browser • QC Charts • Precision control • Accuracy control • Exporting

  12. Data Chart Selected Chart QC Chart Standard deviation lines Vertical cursor Horizontal cursor Vertical cursor pane Overall statistic pane Reference material pane Status bar information

  13. Chart navigation CHART CURSORS The chart has two cursor to select data points: VERTICAL CURSOR : Moves between data points. The current point’s data is displayed in the bottom right cursor pane. HORIZONTAL CURSOR: Use to for statistical evaluation. As the cursor moves the count of points that is below or above the mean value is displayed in the status bar. To move the cursor in larger increments use the <ctrl> key in combination with the up or down arrow keys. TIP: Use the ctrl+left-arrow or ctrl+right-arrow keys to quickly move to data points that intercept the horizontal cursor. The status bar displays the number of points that are above or below the horizontal cursor position

  14. Chart toolbars Export chart into Excel as a metafile Filter between two dates. Opens the report or worksheet associated with the selected data point Hide / unhide data points. Hidden points are excluded from statistical calculations Range selection for duplicate statistics Edit a note for the selected data point Chart data zooming Distribution chart Press the <#> button to load date from current cursor position.

  15. Data pane REFERENCE PANE STATISTIC PANE CURSOR PANE The DATA WINDOW is divided into three panes: REFERENCE PANE: This is the reference material pane, reference data from the selected analysis. STATISTIC PANE: This displays the statistic of all the data points, excluding the hidden values. CURSOR PANE: the data related to the current selected point.

  16. Frequency distribution chart mode Mean n = Population r = Range x = Mean s = Std Dev. s+1 s-1 s-2 s+2 Count found in this range s+3 MaxVal MinVal MaxVal + Dx This is the normal distribution chart. The Histogram bar width (class interval) is the difference between the Max and Min value divided by 20. Hidden values are not included. Total number of bars is 21 in order included the last point (NOTE: correct interval adjusting will be available in a future release).

  17. ** Precision ** • QC browser • QC Charts • Precision control • Accuracy control • Exporting

  18. Precision control charts Precision control charts are the one associated to replicates and are used to estimate the precision of a process. The term precision is used to describe the reproducibility of results. It can be defined as the agreement between the results of repetitive measurements made in an identical fashion. Accuracy control charts monitor the accuracy of a measurement process.

  19. R = the difference between duplicates • N = The number of duplicate pairs Replicate statistic For routine control of precision, the standard deviation of the difference (R) is used. This is best calculated from a large number (>25) of results of replicate analyses, of different samples, carried out by the twin-stream method. The objective is to obtain a strict, but realistic standard deviation, to control the efficiency of routine analysis. The difference between the two results is a measure of the quality of the analyst's work and the reproducibility of the method. • To ensure that the estimation of the standard deviation ‘s’ is reliable, you should consider the following: • N should be at least 20 • The concentrations of the samples where the duplicates where selected do not differ by orders of magnitude. • The sum of the difference between the individual duplicates (with the sign taken in account) must be close to zero.

  20. Dup test

  21. Replicate Setup Describe this set of duplicates, who is using it, etc. Use meaningful names for the Duplicate QC’s so to describe the range of data stored in the duplicate Only values in this range will be loaded into this file. List of tests included in this duplicate QC. You can load all test from the Test Library and then remove the one not desired.

  22. Precision Charts • The routine inclusion of duplicates into a measurement system permits the visual monitoring of the precision using range charts. • The following range control charts are provided by OnLQC: • Replicate Ro: plots Ro = Dup1-Dup2 • Replicate R%: plots R% = (DupMax-DupMin)/DupMax*100 • Range Control charts • Range Ratio charts • Cumulative sum of difference • Range performance charts

  23. Replicate Ro Ro is plotted around the Zero line The Replicate Ro chart plots Ro (Diff = Dup1 – Dup2) over recorded time.

  24. Replicate % The Replicate % chart plots the difference between two duplicates expressed in R% = (DupMax-DupMin)/DupMax*100 over recorded time.

  25. Range control 0% 5% Above 2.51 50% A range control chart for replicate measurements is constructed by calculating a central line or mean range (R ) a warning limit (WL=2.51) and a control limit (CL=3.27). A minimum of 20 range values should be used to construct the range control chart. The plotted value is the absolute( Dup1-Dup2).

  26. Linear Regression Least squares solution For the Range Ratio Chart and the Range Performance Chart it is necessary to calculate the ratio Rr=Ro/Rc, where Rc is the expected difference between the duplicate results obtained from a linear regression: Rc = b0+b1*X

  27. Range Ratio When duplicate pairs are run as part of the routine process, the difference between the measurements is calculated as Ro and ratioed to the expected range for the mean concentration of the duplicate pair Rc obtained from the plot. This gives the range ratio Rr (Rr = Ro/Rc) which is plotted on a graph with horizontal lines drawn at 1.0, 2.51 and 3.27 (no units).

  28. Range Performance To develop the range performance chart, the mean ranges R are plotted against concentration. Control lines are plotted on the chart in a manner similar to those on the range control chart. Subsequent range values obtained from duplicates run as part of the routine work are plotted on the chart and the same statistical controls apply in this instance as in the range control - 50% of the values plotted should lie below the 0.845R line, only 5% above the 2.51R line and no values above the 3.27R line.

  29. ** Accuracy ** • QC browser • QC Charts • Precision control • Accuracy control • Exporting

  30. Accuracy control charts • Accuracy control charts monitor the accuracy of a measurement process. This charts are constructed with the results obtained from the reference materials included in the measurement process along with the samples. There are many different types of charts, but these are the three most commonly used: • Shewhart or X Control chart • X-Bar chart (not implemented yet) • Cumulative Sum (CuSum) control chart • Accuracy is defined as “The nearness of a result or of the mean of a set of results to the true or accepted value”. • Precision control charts are associated with replicates and are used to estimate the precision of a process.

  31. Shewhart Chart Hided data point (Green mark) Value out of the chart (Yellow mark) The Shewhart chart plots data concentration over recorded time (sequence). The data is adjusted to the chart window for best fit. With <-> and <+> keys the chart can be zoomed in or out. The StdDev warning limits are: Std+3 = Mean + 3 * StdDev (UCL) Std-3 = Mean - 3 * StdDev (LWL) Std+2 = Mean + 2 * StdDev (UWL) Std-2 = Mean - 2 * StdDev (LCL) Std+1 = Mean + 1 * StdDev Std-1 = Mean - 1 * StdDev

  32. X-Control chart The X-Control chart is similar to the Shewhart chart but with the difference that a green band is drawn between the Cert Min and Cert Max values

  33. Cumulative Sum + +… + The cumulative sum (CumSum) plots the cumulative sum of the differences between the Data values and the Certified value. This chart is more sensitive to the bias in the measuring system. In a system that is in control the chart should be a random horizontal line, with slightly differences. If the chart falls (like the one above) or rises over the time, is an indication of a process with a systematic error.

  34. ** Exporting ** • QC browser • QC Charts • Precision control • Accuracy control • Exporting

  35. Exporting QC File Export to excel Use this button to export all the data from the selected QC to and Excel file Customs reports and statistics can then be generated using Excel

  36. Lunch it from the chart Exporting QC Charts QC charts can be exported as METAFILES to Excel. The METAFILE format allows the charts the be copied and resized without loosing any detail. This will help create great looking customs reports and documentation. Use copy/paste to copy this chart into an other application

  37. QC Charts are metafiles LQC export charts using the METAFILE format instead of BITMAP format. METAFILES are files that store the drawing instructions needed to reproduce the chart. The advantage of this format is that no information is lost when the charts is resized.

  38. **closing** Thank you for your time ! © 2007 by Online LIMS www.online-lims.com Total slides: 38

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