Graphical Displays of Data EPSY 5245 Michael C. Rodriguez.

Graphical Displays of Data

EPSY 5245Michael C. Rodriguez

Graphical Display of Data

• Format depends on purpose• Make important data stand out• Draw attention to the important features of

the data• Focus on the data of concern• Proofread and ask:

– Does this say what I need it to say?

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Graphs• Everything on the graph should be explained

– Title (descriptive & distinguishing, yet brief)– Labels (scale metric, categories, data points)– Legend (should also have a title)

• Items on the graph should be easily distinguished:– Design (draws focus to important data)– Shading (remains distinguishable after poor copying)– Size (legibility)

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Graphs

• The scale should be sensible – showing the full range of possible values

• Avoid 3-D, creating distortion and false contrasts; unless you have a genuine 3rd dimension

• At a minimum, displayed scale values should be consistent across a set of graphs

• Date and source the graphs– At the bottom, place the data the graph was

produced and ID the producer10

2002 2003 20040

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10

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Program Improvement Results

3rd4th5th

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2002 2003 20040

10

20

30

40

50

60

70

80

90

100

Program Improvement Results

3rd4th5th

Year of Program

Perc

ent I

mpr

ovin

g

Grade

12

2002 2003 20040

10

20

30

40

50

60

70

80

90

100

Program Improvement ResultsPercent Improving on Reading MCA by Grade over Time

3rd4th5th

Year of Program

Perc

ent I

mpr

ovin

g

Grade

13

Note: Numbers above the bards report the percentage of students who improved by 10% or more.

2002 2003 20040

10

20

30

40

50

60

70

80

90

100

35 3845

26 28

4340 4347

Program Improvement ResultsPercent Improving on Reading MCA by Grade over Time

3rd4th5th

Year of Program

Perc

ent I

mpr

ovin

g

Grade

MCR, 2/25/08

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Tables

• Date (what time period is covered)• Complete title (descriptive and brief)• Labels should be descriptive and consistent

across the set of tables• Decided between counts and percentages

– Are the proportions, actual numbers, or both important?

• Always report totals and sample sizes– Allow readers ability to recalculate percentages.

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Table Notes

• Notes to tables should provide details that may or may not be in the text, but are important to interpret the table results– Sources of the data– Special statistical tests– Modified data (based on subgroups, or excluding

some cases)– Missing data (including number)

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How often do you speak English at home?

Frequency Percent Valid PercentCumulative Percent

Validalways or almost always 6049 88 88 88

sometimes 783 11 11 99

never 80 1 1 100

Total 6912 100 100

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Table 1How often do you speak English at home?

Response Count Percent

Always or almost always 6049 88

Sometimes 783 11

Never 80 1

Total 6912 100

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Table 1How often do you speak English at home?

Were you born in the USA?

No Yes

Count % Count % Always or almost always 312 50 5737 91

Sometimes 271 44 512 8

Never 40 6 40 1

Total 623 100 6289 100

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Figure 1. How often do you speak English at home?

always or almost always sometimes never0

10

20

30

40

50

60

70

80

90

100

88

11

1

Perc

ent

20

Always or almost always Sometimes Never0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Yes

No

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No Yes0

10

20

30

40

50

60

70

80

90

100

NeverSometimesAlways or almost always

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n PercentValid

PercentCumulative

Percent

Valid Finish primary school 219 3.2 3.5 3.5Finish some secondary school 678 9.8 10.7 14.2

Finish secondary school 1602 23.2 25.3 39.4

Some vocational education 579 8.4 9.1 48.6

Some university 1688 24.4 26.6 75.2

Finish university 1570 22.7 24.8 100.0

Total 6336 91.7 100.0

Missing I don't know 419 6.1

System 157 2.3

Total 576 8.3

Total 6912 100.023

What is the highest education level of your mother?

76543210

Freq

uen

cy2,000

1,500

1,000

500

0

Mean =4.19Std. Dev. =1.488

N =6,33624

FRL1.000.800.600.400.200.00

Fre

qu

ency

12.5

10.0

7.5

5.0

2.5

0.0

Histogram

Mean =0.67Std. Dev. =0.171

N =56

Percent on FRL in SPPS

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ELL1.000.800.600.400.200.00

Fre

qu

ency

8

6

4

2

0

Histogram

Mean =0.25Std. Dev. =0.101

N =56

Percent in ELL in SPPS

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BelowAve100.0080.0060.0040.0020.000.00

Fre

qu

ency

12.5

10.0

7.5

5.0

2.5

0.0

Histogram

Mean =40.79Std. Dev. =12.102

N =56

Percent Below Average in Reading

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% FRL v. % Below Average

FRL1.000.800.600.400.200.00

Belo

wA

ve

60.00

40.00

20.00

0.00

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Corrected Scales

Proportion FRL1.00.80.60.40.20.0

% B

elo

wA

ve

100

80

60

40

20

0 Proportion on Free & Reduced Lunch29

Highest Mother Ed & Math Score

What is the highest education level of your mother?

654321

Mat

h S

core

(M

ean

= 5

00, S

D =

100

)

800

700

600

500

400

300

200R Sq Linear = 0.065

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Highest Mothers Ed & Math Score

What is the highest education level of your mother?

Finish university

Some university

Some vocational education

Finish secondary

school

Finish some

secondary school

Finish primary school

95%

CI M

ath

Sco

re (

Mea

n =

500

, SD

= 1

00)

600

550

500

450

400

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Crosstab

Usually Speak English at Home Total

No Yes NoWhat is the highest education level of your mother?

Finish primary school

116 103 21953.0% 47.0% 100.0%

Finish some secondary school

120 558 67817.7% 82.3% 100.0%

Finish secondary school

151 1451 16029.4% 90.6% 100.0%

Some vocational education

74 505 57912.8% 87.2% 100.0%

Some University

136 1552 16888.1% 91.9% 100.0%

Finish University

135 1435 15708.6% 91.4% 100.0%

Total 732 5604 633611.6% 88.4% 100.0%

What is the highest education level of your mother? * Usually Speak English at Home Crosstabulation

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What is the highest education level of your …

Finish university

Some university

Some vocational education

Finish secondary

school

Finish some secondary

school

Finish primary school

Per

cen

t30.0%

20.0%

10.0%

0.0%

YesNo

Usually Speak English at Home

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Wh

at is

th

e h

igh

est

edu

cati

on

leve

l of

you

r m

oth

er? Finish university

Some university

Some vocational education

Finish secondary school

Finish some secondary school

Finish primary school

Percent30.0%20.0%10.0%0.0%

YesNo

Usually Speak English at Home

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Usually Speak English at HomeYesNo

Per

cen

t100.0%

80.0%

60.0%

40.0%

20.0%

0.0%

Finish universitySome university

Some vocational education

Finish secondary school

Finish some secondary school

Finish primary school

What is the highest education level of your

mother?

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Final Notes

• Make it easier for the reader• Keep graph and associated text (explanation)

on the same page; text first, followed by graph• Graphs and associated tables can be

presented, if discussed in the text – otherwise put associated tables in the appendix (especially if tables are large)

• Use consistent font – so that when printed, is 12 pt.

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