1. Accuracy and Precision
Measurements
Accuracy and Precision
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2. Timberlake LecturePLUS
Accuracy
How close a measurement is to the actual or true value
good accuracy
true value
poor accuracy
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3. Timberlake LecturePLUS
Precision
How well several measurements agree with each other
good precision
poor precision
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4. Accuracy and Precision
What can you say about the accuracy and precision in each of the following:
Good precision, poor accuracy
Good precision, good accuracy
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5. Timberlake LecturePLUS
In your new job, you are to make the pizzas the size shown above. Your first four pizzas are shown below.
What can you say about the accuracy and precision of your pizzas?
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The next four pizzas.
What can you say about the accuracy and precision of the next four pizzas?
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7. Timberlake LecturePLUS
Accuracy is improving.
The two pizzas in the center show good accuracy. However, the precision is poor.
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Pizza Precision
You have very good precision, but poor accuracy.
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9. Timberlake LecturePLUS
Learning Check!
Match the following terms
1) Accuracy 2) Precision
___ How close a measurement is to the
true value.
___ How close several measurements
are to each other.
Can you have data that are precise, but not accurate? Why or why not?
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10. Timberlake LecturePLUS
Solution
Match the following terms
1) Accuracy 2) Precision
_1_ Is how close a measurement is to the
true value.
_2_ Is how close several measurements
are to each other.
Yes. Data can be precise, but not come close to the true value.
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11. Precision and Accuracy
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12. How Precise Can Our Measurements Be?
You can only be as precise as your ruler or instrument allows you.
Find the interval between the smallest marks on your ruler
Move your decimal place one spot to the left.
This is how precise you can be: estimate the last digit in your measurement and go to that many decimal places in the measurement you record.
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