Timberlake LecturePLUS 1

Chapter 1Measurements

Accuracy and Precision

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Accuracy

How close a measurement is to the actual or true value

good accuracy

true value

poor accuracy

true value

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Precision

How well several measurements agree with each other

good precision

poor precision

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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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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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What can you say about the accuracy and precision of the next four pizzas?

The next four pizzas.

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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. I think the customers will want the pizzas made larger.

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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?

Learning Check AP1

Timberlake LecturePLUS 10

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.

Solution AP1

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Learning Check AP2

How will each of the following affect accuracy and precision?

1. A meter stick that is missing the first

centimeter.

2. A scale that has a zero point that is

really five pounds above zero.

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Solution AP2

How will each of the following affect accuracy and precision?

1. The shortened meter stick will produce measurements that have poor accuracy, but good precision is possible.

2. The poorly calibrated scale will give a weight that is not accurate, but good precision is possible.

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Learning Check AP3

True(1) or false (2). Measurements can

have

poor accuracy and poor precision

good accuracy and poor precision

poor accuracy and good precision

good accuracy and good precision

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Learning Check AP3

True(1) or false (2). Measurements can

have

poor accuracy and poor precision

good accuracy and poor precision

poor accuracy and good precision

good accuracy and good precision

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