It is important to be able to MAKE measurements and to decide whether a measurement is CORRECT. --...
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Transcript of It is important to be able to MAKE measurements and to decide whether a measurement is CORRECT. --...
![Page 1: It is important to be able to MAKE measurements and to decide whether a measurement is CORRECT. -- Are you certain that your measurement is correct? HOW.](https://reader037.fdocuments.net/reader037/viewer/2022103015/5515177d55034673228b4cb3/html5/thumbnails/1.jpg)
It is important to be able to MAKE measurements and to decide whether a measurement is CORRECT.
-- Are you “certain” that your measurement is correct? HOW “certain” are you???
2.32.344 gg
A measurement is a quantity that has both a number and a unit.
36.36.11 mLmL 16.5 16.5 Years OldYears Old
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Accuracy, Precision, and Error
Here is an example:Here is an example:
How old is this cat?How old is this cat?
_____ Months_____ Months (everyone must guess)(everyone must guess)
How do you evaluate accuracy and precision? (Your thoughts???)
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• Accuracy is a measure of how close a measurement comes to the actual or true value of whatever is measured. (closest to TRUE Value)
• Precision is a measure of how close a series of measurements are to one another. (repeated Save Value)
Accuracy and Precision
Who was more ACCURATE and more PRECISE in your measurements of the age of my cat?
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AccuracyAccuracy – closest to TRUE Value – closest to TRUE ValuePrecisionPrecision – repeated Same Value – repeated Same Value
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Determining Error
• The experimental value (EV) is the value measured in the lab. (by the student)
• The accepted value (AV) is the correct value based on reliable references.
• The error is the difference between the experimental value and the accepted value
Error = experimental value (EV) - accepted value (AV) (measured by student) - (correct value)
What is the error in your measurement of the age of my cat?
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The percent error is an absolute valueabsolute value (there is no positive or negative value.)
Percent Error
Percent Error = x 100% EV - AVAV
What is the percent error in your measurement of the age of my cat?
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Error VS Percent ErrorWhat is Mr. Pearson’s weight? Experimental Value (EV) = 115 kgActual Value (AV) = 110 kg
= 115 kg – 110 kg x 100 % = 4.5%
Error = EV – AV
Percent Error = x 100% EV - AVAV
= 115 kg – 110 kg = 5 kg
110 kg
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Error VS Percent ErrorWhat is the weight of my car? Experimental Value (EV) = 3,585 kgActual Value (AV) = 3,580 kg
= 3,585 kg – 3,580 kg x 100 % = 0.14%
Error = EV – AV
Percent Error = x 100% EV - AVAV
= 3,585 kg – 3,580 kg = 5 kg
3,580 kg
![Page 9: It is important to be able to MAKE measurements and to decide whether a measurement is CORRECT. -- Are you certain that your measurement is correct? HOW.](https://reader037.fdocuments.net/reader037/viewer/2022103015/5515177d55034673228b4cb3/html5/thumbnails/9.jpg)
What is Mr. Pearson’s weight? Error VS Percent Error
What is the weight of my car? Error = 3,585 kg – 3,580 kg = 5 kg % Error = 3,585 kg – 3,580 kg x 100 % = 0.14%
3,580 kg
% Error = 115 kg – 110 kg x 100 % = 4.5% Error = 115 kg – 110 kg = 5 kg
110 kg