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# Topic: Accuracy and precision

 Clemson U. Physics Tutorial: Accuracy & Precision The magnitude of the error is due to the precision of the measuring device, the proper calibration of the device, and the competent application of the device. To determine the error associated with a measurement, scientists often refer to the precision and accuracy of the measurement. The precision of an experiment is a measure of the reliability of the experiment, or how reproducible the experiment is. In this figure, we see that the marksman's instrument was quite precise, since his results were uniform due to the use of a sighting scope. phoenix.phys.clemson.edu /tutorials/ap/index.html   (529 words)

 Accuracy and precision Summary Accuracy is the closeness of an experimental measurement to the "true value"; (i.e., actual or specified) of a measured quantity. The accuracy and precision of a measurement process is usually established by repeatedly measuring some traceable reference standard. Precision is usually characterised in terms of the standard deviation of the measurements, sometimes called the measurement process's standard error. www.bookrags.com /Accuracy_and_precision   (2088 words)

 physics - Accuracy and precision In a common analogy illustrating the difference between accuracy and precision, repeated measurements are compared to arrows that are fired at a target. The accuracy and precision of a measurement process is usually established by repeatedly measuring some traceable reference standard. Precision is usually characterised in terms of the standard deviation of the measurements, sometimes called the measurement process's standard error. www.physicsdaily.com /physics/Accuracy_and_precision   (484 words)

 Science 122 Accuracy vs. Precision The darts are not clustered together and are not near the bull's eye. The darts are tightly clustered and their average position is the center of the bull's eye. Does that help to understand the distinction between accuracy and precision as the terms are used in the science of measurement? honolulu.hawaii.edu /distance/sci122/SciLab/L5/accprec.html   (0 words)

 SparkNotes: Units, Scientific Notation, and Significant Figures: Accuracy vs. Precision In the previous section on significant figures we dealt obliquely with the accuracy of an experiment. Precision is the degree to which the results of multiple repeat experiments agree with one another. Accuracy is the degree to which the results of an experiment agree with the true or known value. www.sparknotes.com /physics/units/section4.rhtml   (257 words)

 INFO: Precision and Accuracy in Floating-Point Calculations There are many situations in which precision, rounding, and accuracy in floating-point calculations can work to generate results that are surprising to the programmer. The result of multiplying a single precision value by an accurate double precision value is nearly as bad as multiplying two single precision values. It demonstrates that even double precision calculations are not perfect, and that the result of a calculation should be tested before it is depended on if small errors can have drastic results. support.microsoft.com /kb/125056   (0 words)

 Accuracy and Precision   (Site not responding. Last check: ) The term Accuracy refers to how close a result or measurement is to the actual value. The accuracy of the archer would be determined by the location of the group of arrows. The goal of any chemist in the laboratory is to achieve both accuracy and precision in their experimental results and measurements. www.vanderbilt.edu /AnS/Chemistry/courses/chem104/experiment1/accuracy/accuracy.htm   (126 words)

 Handling Accuracy and Precision Precision of an Instrument is the ability to show repeatable, reliable and the same measurement each time." It is an indicator of the scatter in the data. The accuracy and precision of a measurement process is usually established by repeatedly measuring and obtaining a specified standard measurement. Hence, to maintain full accuracy, the amplifier output must settle to a level given by the magnitude of 0.5 LSB before the next conversion, and is on the order of several tenths of a millisecond for most boards. articles.jimtrade.com /1/210.htm   (817 words)

 Accuracy and Precision > Intelligent Enterprise: Better Insight for Business Decisions Techniques to improve accuracy and precision are more widely understood than applied, perhaps because they're often proposed out of sensible context, sold as ends in themselves rather than as one means toward a goal that is influenced by many factors. The government conducts an accuracy and coverage evaluation of the census, an independent survey to assess the source and extent of error, but judged that statistically adjusting 2000 census results to improve accuracy would likely introduce errors greater than those adjustments would eliminate. Fixing results may not improve their accuracy because of limitations in the sensitivity of the measurement instrument and of the correction techniques, reinforcing the importance of designing and building accuracy into processing systems. www.intelligententerprise.com /showArticle.jhtml?articleID=17701622   (1093 words)

 WHAT IS THE DIFFERENCE BETWEEN ACCURACY AND PRECISION?   (Site not responding. Last check: ) Accuracy is defined as, "The ability of a measurement to match the actual value of the quantity being measured". Precision is defined as, "(1) The ability of a measurement to be consistently reproduced" and "(2) The number of significant digits to which a value has been reliably measured". The goal of any meteorological instrument is to have high accuracy (sensor matching reality as close as possible) and to also have a high precision (being able to consistently replicate results and to measure with as many significant digits as appropriately possible). www.theweatherprediction.com /habyhints/246   (478 words)

 Fuel Quality Accuracy and Precision   (Site not responding. Last check: ) Accuracy can also be defined as the agreement of the average value of a set of measurements on the same material with an accepted value for that material (i.e. Precision is the agreement of each value in a set of measurement on the same material with the average value of the set (i.e. Without the precision data the test method would be rendered useless and could not be used in any specification or regulation, as without the precision data there would be no guarantee, promise or assurance that the results produced are acceptable. www.intertek-cb.com /newsitetest/services/petrotesting/fuelqualaccuracyprecision.shtml   (1911 words)

 Accuracy & Precision   (Site not responding. Last check: ) Precision is the dispersion or closeness of the agreement between successive measurements of the same quantity. Low precision will cause a widely dispersed curve with a low maximum, since the values of many of the measurements may differ significantly from the mean (curve B). Since there is no necessary connection between accuracy and precision, it is possible to obtain measurements of high precision with a faulty measuring device. www.pitt.edu /~n3lsk/accprecproc.html   (1647 words)

 Accuracy and Precision by SGS Accuracy gives an indication how close a test result is to the "true" value, or, more practically, how close it might be to the average of the results from a number of independent laboratories. Laboratories monitor their accuracy either by repeatedly measuring samples or things with known values, or by comparing themselves to other laboratories in proficiency trials. Precision is a measure of how repeatable a result might be. www.sgs.com /accuracy_and_precision_nz.htm   (248 words)

 Error, Accuracy, and Precision Accuracy is an issue pertaining to the quality of data and the number of errors contained in a dataset or map. Accuracy and precision are a function of the scale at which a map (paper or digital) was created. Accuracy and precision are tied to the original map scale and do not change even if the user zooms in and out. www.colorado.edu /geography/gcraft/notes/error/error.html   (4168 words)

 Information Internet: Chemistry, Accuracy vs. Precision in   (Site not responding. Last check: ) The accuracy of an analytical measurement is how close a result comes to the true value. Determining the accuracy of a measurement usually requires calibration of the analytical method with a known standard. Precision is the reproducibility of multiple measurements and is usually described by the standard deviation, standard error, or confidence interval. library.thinkquest.org /10679/chemistry/chem_acpr.html   (53 words)

 Error, Accuracy, and Precision Accuracy is an issue pertaining to the quality of data and the number of errors contained in a dataset or map. Accuracy and precision are a function of the scale at which a map (paper or digital) was created. Accuracy and precision are tied to the original map scale and do not change even if the user zooms in and out. www.forestry.umt.edu /academics/courses/for503/GIS_Errors.htm   (4426 words)

 accuracy and precision Though the subjects of accuracy, precision and randomization should be known to all scholars using measurements, I am afraid that that is simply not the case. The reason that these shortcomings are important is that when "facts" or "results" are reported and stored they indeed should be tagged with some characterization of their accuracy and precision. One must remember that the problem of accuracy and precision were around before computers but with computers the words took on an additional connotation. lists.ucles.org.uk /public/ims-qti/2003-February/000533.html   (1213 words)

 CSA Newsletter, Spring '02: Measuring with Precision and Accuracy Using the more precise measurement suggests that the building was constructed to incredibly tight tolerances, which it was, but it also suggests that the precise dimensions were planned, which is not the case. precision is unnecessary to show tight building tolerances and misleading if it indicates either precise planning of block dimensions or precise measurement by the ancients. Second, that level of precision is meaningless because it is the result of a process that has so many opportunities for error -- in many instances error that propagates -- that the precise numbers must be seen as inaccurate. csanet.org /newsletter/spring02/nls0206.html   (1320 words)

 MythHome: Precision and Accuracy   (Site not responding. Last check: ) Precision and Accuracy are the quantitative equivalent of Reliability and Validity. Precision means that all the measurements of a numerical value are close one anoother. Their accuracy was evaluated by another eminent physicists, P.T. Birge, an authority on measurements and errors, who studied their techniques and data and conccluded that their measurements was probably within 4 km/sec of the correct value. www.mythome.org /PandA.html   (752 words)

 Precision and Accuracy ......... Because the smallest unit on the ruler you are using is one centimetre, the precision of your measurement is to the nearest centimetre. Because the smallest unit on the ruler you are now using is one millimetre (one tenth of a centimetre), the precision of your measurement is to the nearest millimetre, or tenth of a centimetre. The accuracy of a measurement is the difference between your measurement and the accepted correct answer. www.worsleyschool.net /science/files/precision/andaccuracy.html   (887 words)

 Accuracy vs One important distinction between accuracy and precision is that accuracy can be determined by only one measurement, while precision can only be determined with multiple measurements. Precision has nothing to do with the true or accepted value of a measurement, so it is quite possible to be very precise and totally inaccurate. For example, if a student is reading the level of water in a graduated cylinder that has lines to mark each milliliter of water, then he or she should report the volume of the water to the tenth place (i.e. www.sftw.umac.mo /~fstai/Accuracy-Precision.htm   (429 words)

 AYE Conference articles - Estimates: Precision vs. Accuracy by Johanna Rothman Precision is the exactness of the measurement, the number of decimal places. Accuracy meant how many times we could make the robot arm move to that precise place. Be precise at the end of a project, when you file your project information, and manage the data that was part of the project’s outcome. www.ayeconference.com /Articles/Estimateprecisionaccuracy.html   (934 words)

 Scientific English--Accuracy and Precision   (Site not responding. Last check: ) Accuracy is the degree to which a result agrees with the theoretical value. A precise inaccurate archer will be able to repeat the position of the arrows very well, but the position of the arrows averaged over a number of shots will be far from the center of the target. Both accuracy and precision are useful to know when evaluating experimental results, especially when introducing a new technique or measuring fundamental constants. users.wpi.edu /~nab/sci_eng/99_Jun_14.html   (323 words)

 Accuracy and Precision in POCT Reliable results from patient samples, regardless of whether they are analysed at the bedside by POCT or in the laboratory, must be accurate and precise, no matter which methodology is used. Accuracy and Precision equals Reliability: this is an axiom of laboratory work and one of those rules of thumb that gets drummed into you as a laboratory trainee. Statistical analyses of results will determine the levels of Accuracy and Precision: calculation of Means, Standard Deviations (SD) and Coefficients of Variation (CV) will be sufficient to determine whether results are acceptable. www.cdhb.govt.nz /ch_labs/accuracy_and_precision.htm   (317 words)

 Journal of Vision - Accuracy and precision of objective refraction from wavefront aberrations, by Thibos, Hong, ... We determined the accuracy and precision of 33 objective methods for predicting the results of conventional, sphero-cylindrical refraction from wavefront aberrations in a large population of 200 eyes. Accuracy for predicting defocus (as specified by the population mean error of prediction) varied from –0.50 D to +0.25 D across methods. Precision of these estimates (as specified by 95% limits of agreement) ranged from 0.5 to 1.0 D. All methods except one accurately predicted astigmatism to within ±1/8D. journalofvision.org /4/4/9   (388 words)

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