November 6-9, Seattle, WA

Bad Reports: Fixing Their Mistakes

Roger NobleConsultant

LobsterPot Solutions

2

My bad report

NSW Police reportJust an example, not really from the NSW Police Dept. (source data.gov.au)

Report is used to: • Track incident response times• Incident rates across divisions• Incident rates by offence

BID-210

3 November 6-9, Seattle, WA

Bad ReportDemo

4

First Some Theory

What are we trying to communicate?

Remove non-data pixels and chartjunk

Increase data density

Use colour sparingly

BID-210

5

Data ink and non-data ink

BID-210

6

Chartjunk

= 38.7%

BID-210

7

Colour

BID-210

0

10

20

30

40

50

60

70

80

ThingsStuffBitsBobsWhatsitWidgetWhirlyBytesPickleTomato

8

Data-Ink Ratio

BID-210

Ink used to present the data

Total ink used

9

Process for continual improvement

1. Identify non-data pixelsa. Can it be removed?b. Can it be deemphasised?

2. Identify data pixelsa. Is it meaningful?b. Can it be emphasised?

3. Repeat

BID-210

10 November 6-9, Seattle, WA

Let’s fix it!Demo

11

Charts

BID-210

12

Charts

BID-210

13

Charts

BID-210

14

Data types

Dimensions• Nominal Location• Ordinal Days of week• Interval Time

Measures• Additive Sales amount• Non-additive Temperature

BID-210

15

Data types - Charting

Dimensions Measures Nominal Ordinal Interval Additive Non-

additive

MeasuresAdditive Non-additive

BID-210

16

Charting – Line vs Bar

BID-210

Nominal

17

Charting – Line vs Bar

BID-210

Nominal

18

Charting – Line vs Bar

BID-210

Interval

19

Charting – Line vs Bar

BID-210

Interval

20 November 6-9, Seattle, WA

Let’s fix it!Demo

21

Tables

BID-210

22

Tables

Remove unnecessary colour and gridlines

BID-210

23

Tables

Remove gridlines and unnecessary colour

BID-210

24

Tables

Add lines and emphasis where necessary

BID-210

25

Tables

Add white space to aid with reading

BID-210

26

Tables

Add white space to aid with readingWhite space allows the eye to easily scan down columns and across rows

BID-210

27

Indicators

Be optimisticadd indications only for exceptions

BID-210

28

Indicators

Be optimisticadd indications only for exceptions

BID-210

29 November 6-9, Seattle, WA

Let’s fix it!Demo

30

Problems with Pie charts

Requires mental conversion from size/angle to percentage.

Works well when values are close to 25% and 50% (90o and 180o)

1234

BID-210

31

Problems with Pie charts

Distortion from perspectiveSlices that are closer appear larger than they are

1234

BID-210

32

Problems with Pie charts

Actual values can be listed in a smaller space (higher data-ink ratio)

1234

=1. 32% (40)2. 24% (30)3. 20% (25)4. 24% (30)

BID-210

33

Problems with Pie charts

Patterns are harder to perceive

BID-210

1

2

3

4

56

7

8

9

10

0 2 4 6 8 10 120

2

4

6

8

10

12

14

VS

34

Area based charts

Area is difficult to quantifyBubbles must be sized by area not diameter (or radius or circumference)

IncorrectSized by diameter

CorrectSized by area

BID-210

N 2N

35

What else is bad?

Size can be perceived differently based on surroundings

BID-210

36 November 6-9, Seattle, WA

Let’s fix it!Demo

37

Summary

Identify key information

Improve the data-ink ratio (remove chartjunk)

Use whitespace to aid in scanning rows and columns

Be optimistic with indicators

Only use area based charts when accuracy isn’t important

BID-210

38

Recommended Reading

Edward Tufte

Steven Few

Also: William S. Cleveland, Colin Ware, Nathan Yau and Benjamin Willers

BID-210

39November 6-9, Seattle, WA

Thank youfor attending this session and the 2012 PASS Summit in Seattle