{"id":1496,"date":"2020-03-31T11:56:46","date_gmt":"2020-03-31T10:56:46","guid":{"rendered":"https:\/\/sites.manchester.ac.uk\/bioms-users\/?p=1496"},"modified":"2020-04-07T15:18:11","modified_gmt":"2020-04-07T14:18:11","slug":"facility-is-accuracy-important","status":"publish","type":"post","link":"https:\/\/sites.manchester.ac.uk\/bioms-community\/2020\/03\/31\/facility-is-accuracy-important\/","title":{"rendered":"Facility: Is accuracy important?"},"content":{"rendered":"

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This post follows on from a conversation with Christoph Borchers of the University of Vancouver in which he states \u201cAccuracy is not important, precision is everything\u201d. <\/em>This is a highly provocative statement, especially in the analytical world but is he right?<\/p>\n

To begin with I have to introduce some key analytical terminology:<\/p>\n

Accuracy<\/em><\/strong> \u2013 how close the calculated result is to the true result<\/p>\n

Precision<\/em><\/strong> \u2013 how close replicate measurements are to each other<\/p>\n

Ideally you want to be accurate and precise but can also be accurate but not precise, precise but not accurate or even not accurate or precise. \u00a0<\/p>\n

So how do you know which one of the possibilities describes your analysis? You can easily measure precision but to measure accuracy you have to know what the true value is and this is very difficult when dealing with proteins. Proteins are complicated large molecules and even creating standards is tricky, never mind putting them in \u2018blank\u2019 matrices (the analytical term for the environment your protein would normally be in e.g. plasma or a whole cell lysate) to test your assay.<\/p>\n

If accuracy is so difficult to measure then what relevance does it have? The question here relates to how you apply your quantification. If the measurement is made to determine whether the levels are with a \u2018normal\u2019 range or outside it then what is really required is that the same sample gives the same results over an extended period of time. This now brings in two uses of the concept of precision:<\/p>\n

Intra-batch precision<\/strong><\/em> \u2013 all results within the same batch of samples agree with each other<\/p>\n

Inter-batch precision<\/strong><\/em> \u2013 samples analysed in different batches on different days agree with each other, this can also be termed repeatability <\/strong><\/em>or reproducibility<\/strong><\/em><\/p>\n

It can therefore be seen that actually it is inter-batch precision or repeatability that is the most important. To achieve this you need highly reproducible sample preparation along with robust analytical equipment with systems for tracking variability in performance and correcting for it. This means you need multiplexed methodologies for all stages and preferably robotic automation for sample prep. The mass spec analysis has to be comprehensive and have standards included for correction. Recent presentations by Jennifer Van Eyk (Cedars_Sinai) and Tony Wheaton (Manchester) give some examples of the future and it is big and automated!<\/p>\n

So in summary I\u2019d alter the initial statement somewhat to give:<\/p>\n

\u201cAccuracy is often not as important as inter-batch precision\/reproducibility\u201d<\/strong><\/em><\/p>\n

Tags: #facility, precision, accuracy<\/p>\n

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Related<\/h1>\n

Related posts:<\/h3>
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Facility: Comparing sample preparation techniques<\/h2><\/div><\/div><\/a>
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Facility: DDA vs DIA<\/h2><\/div><\/div><\/a>
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Facility: Sample submission guidelines<\/h2><\/div><\/div><\/a><\/div>
<\/div><\/div><\/div>\n

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