PERCENT PERCENT ERROR, ERROR,

ACCURACY VS. ACCURACY VS. PRECISION PRECISION

AND AND MEASURMENTMEASURMENT

PERCENT ERRORPERCENT ERROR

Your Measured Value – Actual ValueYour Measured Value – Actual Value

Actual ValueActual Value XX 100100

Absolute Value Absolute Value sign: the sign: the

difference difference cannot be cannot be negativenegative

Problem # 

Basic Equation Working Equation

Given variables Solve

Answer3 Sig figsSci Not. Units

Rectangle of Power!Rectangle of Power!

Making sure you subtract the mass of the box, you re-Making sure you subtract the mass of the box, you re-measure the mouse and determine its real mass as 15.0 measure the mouse and determine its real mass as 15.0 grams. What is the percent error?grams. What is the percent error?

Example:Example:

You measure the mass of a mouse to be 14.6 grams. But You measure the mass of a mouse to be 14.6 grams. But because it is constantly jumping around you are not sure because it is constantly jumping around you are not sure if you made an accurate measurement.if you made an accurate measurement.

SO:SO:

*No real mice were hurt in this example.*No real mice were hurt in this example.

Problem # Example

Basic Equation Working Equation

Given variables Solve

Answer3 Sig figsSci Not. Units

Rectangle of Power!

(M-A)/A x 100 (M-A)/A x 100

M = 14.6g

A = 15.0g

(14.6g -

15.0g

15.0g) X 100

2.67% error

ACCURACCURACYACY

PRECISIPRECISIONONvv

s.s. Average is Average is close to the close to the

actual actual number/valunumber/valu

ee

Grouped Grouped close close

togethertogether(small range)(small range)

ACCURACYACCURACY PRECISIONPRECISIONvsvs..

ACCURACYACCURACY PRECISIONPRECISIONvsvs..

Accurate, Precise or Neither

5.1

5.2

5.0

417

638

962

13.24 12.99 13.15

AcceptAccepted ed

Value: Value: 5.145.14

Accepted Accepted Value: Value: 10.2510.25

AcceptAccepted ed

Value: Value: 947947

Trial 1 Trial 2 Trial 3

20.1 15.9 26.8

20.3 13.4 27.4

19.9 23.0 27.2

Accepted Accepted Value: 27.3Value: 27.3AA

PP

NNPP AA PPNN

PP

DETERMINING:DETERMINING: MASSMASS

& & VOLUMEVOLUME

MASSMASS

Turn this Turn this knob to knob to make make sure sure

balance balance is zeroedis zeroed

Tenths Tenths placeplace

Ones Ones placeplace

Tens Tens placeplace

Hundreds Hundreds placeplace

100 200 300 400 500

10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 7 8 9 10

100 200 300 400 500

10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 7 8 9 10

100 200 300 400 500

10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 78 9 10

100 200 300 400 500

10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 7 8 9 10

140.5 g

74.8 g

500 g

30

40

VOLUMEVOLUMEGRADUATED CYLINDER GRADUATED CYLINDER

VS. BURETVS. BURETMEASURES MEASURES THE VOLUME THE VOLUME OF A LIQUID OF A LIQUID

What is What is this this

called?called?The The menimeniscusscus

!!

33.5 mL

MEASURES THE MEASURES THE VOLUME OF A VOLUME OF A

LIQUID RELEASED LIQUID RELEASED (USED IN (USED IN

TITRATIONS) TITRATIONS)

50

40

4.00 mL

10

20

30

40

50

60

70

80

90

100

A

B

C

D

E

100 200 300 400 500

10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 7 8 9 10

100 200 300 400 500

10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 7 8 9 10

100 200 300 400 500

10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 7 8 9 10

100 200 300 400 500

10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 7 8 9 10