Communication – 2:Presentations. Graphics. Design.

Preben Aavitsland

Presentations

Talk to your audience

• Look at them (not at the screen)

• Loud and clear speech

• Hands out of pocket

• Hands away from face

• Use your hands

• Use manuscript only if you have to

Respect the time

• 10 minutes = 10 minutes

• You will use:

–80-100 words per minute

–1 slide per minute

Visual aids

• Transparencies– interactive

– best for lecture

– handouts

• Computer presentations– most flexible

– not always safe

– handouts

Preparation of visual aids

• Text first, then visual aids

• The less fancy, the better– Only very careful use of fancy animation and

colours in PowerPoint

• Always related to what you say

Visual dataTables, graphs, charts, maps

• The simpler the better

• Make them talk

• Walk the public through

• Use the pointer appropriately

Food Specific Attack Rates, Outbreak of Salmonellosis, Prison X, Dover, Delaware, September 1992

6.21.51.3 1.1

Food Specific Attack Rates, Outbreak of Salmonellosis, Prison X, Dover, Delaware, September 1992

Outbreak of Salmonellosis in a Prison, Delaware, 09/1992Food Specific Relative Risks, Saturday September 12, Lunch

Chicken Salad

Bread

Lettuce Leaves

Sliced Tomatoes

Pear Halves

Iced Tea

Margarine

Vegetable Soup

Food

0.5 5 50

Relative Risk (log scale)

Point estimate 95% CI

Graphical visual dataGraphs, charts and maps

• One point per slide

• No 3D

• Appropriate colour palette

Palette for a quantitative variable

Light-dark palette

Gradient of grey

AIDS Annual Rates per 100,000 Population for Cases Reported May 1990 through April 1991

Bad example for oral communication : mixture of analog and digital information + innapropriate color palette

Maine 4.6NH 4.6VT 3.6Mass 15.0Conn 14.9NJ 31.3Del 12.9MD 21.2DC 117.2

11.5

10.2

24.4

18.1

2.2 2.4

12.5

3.0

4.4

6.87.7

19.3

6.7

5.7

3.6

1.1

0.9 4.9

2.4

11.7

8.6

10.3

16.27.2 20.2

33.2

9.1

7.4

11.1

2.6

6.0 9.9

43.26.7

10.14.8

5.0

7.2

3.7

3.5

15.5

Legend (rate per 100,000)

0-5.9

6-11.9

12-19.9

20+

AIDS Annual Rates per 100,000 Population for Cases Reported May 1990 through April 1991

Better presentation for oral communication: analog display + quantitative light/dark palette

Rate per 100,000 population

0.0-5.9

6.0-11.9

12.0-19.9

>20.0

Visual reinforcements:bullet lists

• Leave them alone

• Use keywords

• < 12 lines

• < 5 words per line

• Break line prop-erly

Methods

• We conducted a retrospective cohort survey including all people attending the visit of the park

• A case was defined as a papular or papulo-vesicular pruritic rash, among participants, 12 hours or more after the exposure to seawater

The ”Karaoke slide”

Methods• Survey

– retrospective cohort

– all participants

• Case definition

– rash (papular or papulo-vesicular)

– > 12 hours after exposure

Problems to be solved (I)

• Underreporting

• There is no electronic network due to a lack of PCs,software and trained personell (especially at locallevel) for the processing of epidemiological data,their accumulation, analysis and dissemination

• Insufficient level of epidemiologists' education inmodern epidemiology which limits efficiency ofepidemiologists' work

• The lack of guidelines on surveillance andprevention

Problems - 1

• Underreporting

• No electronic network

• ”Outdated” epidemiologists

• No guidelines

Effective text attributes

Sans serif font

Bold type

Lower case letters

Good contrast

Serif font

Normal type

UPPER CASE LETTERS

Poor contrast

Prefer Avoid

INEFFECTIVE TEXT ATTRIBUTES• SERIF FONT

• THIN FONT

• UPPER CASE LETTERS

• POOR CONTRAST

Ineffective text attributes : the bar code font

Poor contrast

SALMONELLA

Environmental sources of the organism include water, soil, insects, factory surfaces, kitchen surfaces, animal faeces, raw meats, raw poultry, and raw seafood, to name only a few. Raw meats, poultry, eggs, milk and dairy products, fish, shrimp, frog legs, yeast, coconut, sauces and salad dressing, cake mixes, cream-filled desserts and toppings, dried gelatine, peanut butter, cocoa, and chocolate.

Various Salmonella species have long been isolated from the outside of egg shells. The present situation with S. enteritidis is complicated by the presence of the organism inside the egg, in the yolk. This and other information strongly suggest vertical transmission, i.e., deposition of the organism in the yolk by an infected layer hen prior to shell deposition. Foods other than eggs have also caused outbreaks of S. Enteritidisdisease.

Salmonella

Environmental sources of the

organism include water, soil,

insects, factory surfaces, kitchen

surfaces, animal faeces, raw

meats, raw poultry, and raw

seafood, to name only a few. Raw

meats, poultry, eggs, milk and dairy

products, fish, shrimp, frog legs,

yeast, coconut, sauces and salad

dressing, cake mixes, cream-filled

desserts and toppings, dried

gelatine, peanut butter, cocoa, and

chocolate.

Various Salmonella species have

long been isolated from the outside

of egg shells. The present situation

with S. enteritidis is complicated by

the presence of the organism

inside the egg, in the yolk. This and

other information strongly suggest

vertical transmission, i.e.,

deposition of the organism in the

yolk by an infected layer hen prior

to shell deposition. Foods other

than eggs have also caused

outbreaks of S. Enteritidis disease.

Graphics

Contents• Use of graphics

• Graphics in descriptive epidemiology– Time

– Place

– Person

– Clinical features

• Graphics in analytical epidemiology– Comparison

• Designing graphics

Epidemiology

Purpose• Description

– Time– Place– Person– Clinical features

• Comparison– Incidence rate ratio– Risk ratio– Odds ratio

Methods• Surveillance• Outbreak

investigations• Other studies

– Case-control studies– Cohort studies

Use of data graphics?

Analyse data

• Organise

• Summarise

• Explore– trends

– relationships

– errors

Present data

• Communicate

• Paper

• Poster

• Screen

The epidemic curve 1

Figure 1. Reported cases of campylobacteriosis (n=45) in Svolvær, Norway, by

date of onset J anuary and February 1997.

10 = 1 primary case

= 1 secondary household case

5

22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10

J anuary February

The epidemic curve 2

• Histogram– Area proportional to number

– No space between columns

– One population

• X-axis = time– Start before epidemic, continue after

– Interval < 1/4 of incubation period

• Y-axis = number of cases– Usually one square = one case

• Easy to make in Excel

Finding the exposure period.Epidemic curve for an outbreak of hepatitis A

2 8 14 20 26 2 8 14 20 26 1 7

Date

0

5

10

15

Number of cases

one case 30 days

15 days

50 days

Exposure

The arithmetic-scale line graph 1

Figure 2. Incidence rate of gonorrhoea and syphilis in Norway, 1975-1999

0

100

200

300

400

1975 1978 1981 1984 1987 1990 1993 1996 1999Year

Gonorrhoea

Syphilis

Cases per 100,000

Source: Folkehelsa

The arithmetic-scale line graph 2

• For time series

• Show actual changes in magnitude

• X-axis = time

• Y-axis = rate (or number) of cases– Start at 0

– Breaks possible, clearly marked

The semilogarithmic-scale line graph 1

Figure 3. Incidence rate of gonorrhoea and syphilis in Norway, 1975-1999

0,1

10

1000

1975 1978 1981 1984 1987 1990 1993 1996 1999Year

Gonorrhoea

Syphilis

Cases per 100,000

The semilogaritmic-scale line graph 2

• For time series when– interested in rate of change

• Y-axis = rate (or number) of cases, semilog.– Straight slope = constant rate of change

– Steep slope = rapid change

– Parallell lines = same rate of change

– Start at lowest cycle, e.g. 0.1-1 or 1-10

– No breaks

• X-axis = time

Gonorrhoea - by race and ethnicity, United States, 1981-1993

1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993

Year

0

500

1000

1500

2000

2500Notification per 100.000 population

White Black Hispanic Other

Source: Summary of Notifiable Diseases, United States 1993

Source: Summary of Notifiable Diseases, United States 1993

Source: Summary of Notifiable Diseases, United States 19931981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993

Year

10

100

1000

10000Notification per 100.000 population

White Black Hispanic Other

Source: Summary of Notifiable Diseases, United States 1991

Gonorrhea - by race and ethnicity, United States, 1981-1993

In graphs...

• Labels for axes, scales and legends

• Legends or keys if >1 variable

• Scale divison, appropriate scale

• Units of measurements in title

• No grid, no numbers

• No 3D

Counts and rates of tuberculosis France, 1996

4-Week Period Ending 31/12/1996 52-Week Period Ending 31/12/1996

Count Rate

Descriptive analysis of place:spot map or area map

Spot map• Count of cases does not represent risk but burden• Areas have different populations• Population may vary over time

– Seasons – Population influx (refugees)

Area map• Rates allow to compare risk across areas• Choice of administrative areas

(Instability of rates in small areas)• Choice of ranges to display data

The two-variable table

Table 1. Cases of Salmonella

Typhimurium-infection by age-group and sex,

Herøy, Norway, 1999

Age group Total

(years) Male Female

0 - 9 7 5 12

10 - 19 5 5 10

20 - 29 5 5 10

30 - 39 1 4 5

40 - 49 2 3 5

50 - 59 0 3 3

60 - 69 2 1 3

70 - 2 4 6

Total 24 30 54

Sex

Grouped bar chart

Figure 1. Cases of S Typhimurium-infection by age-group and sex, Herøy, Norway, 1999

0

2

4

6

8

0 - 9 10 - 19 20 - 29 30 - 39 40 - 49 50 - 59 60 - 69 70 -

Age-group

Male

Female

Number of cases

Stacked bar chartFigure 1. Cases of S Typhimurium-infection by age-group and sex, Herøy, Norway, 1999

0 2 4 6 8 10 12 14

0 - 9

10 - 19

20 - 29

30 - 39

40 - 49

50 - 59

60 - 69

70 -

Age-group

Number of cases

Male

Female

Component bar chart

Figure 1. Cases of S Typhimurium-infection by age-group and sex, Herøy, Norway, 1999

0 %

20 %

40 %

60 %

80 %

100 %

0 - 9 10 - 19 20 - 29 30 - 39 40 - 49 50 - 59 60 - 69 70 -

Age-group

Male FemaleProportional distribution by sex

Bar charts

• Order– Natural

– Decreasing or increasing

• Vertical or horizontal

• Same width of bars

• Length = frequency

• Space between bars and groups, but not within groups

• Tables are often better

Pie chart

Figure 4. Cases of S Typhimurium-infection by age-group, Herøy, Norway, 1999.

21 %

19 %

19 %

9 %

9 %

6 %

6 %

11 % 0 - 9

10 - 19

20 - 29

30 - 39

40 - 49

50 - 59

60 - 69

70 -

The 2x2 table for a cohort study

Table 5. Association between fish consumption and

gastrointestinal illness among customers at Uncle Mike's Fish &

Chips, Cambridge, October 1 2000

Ill Well Total Attack rate

Ate fish 42 16 58 0.72

Did not eat fish 5 59 64 0.078

Relative risk: 9.3 (95% confidence interval 3.9 - 22)

Table from a case-control study

Table 5. Association between exposures and campylobacteriosis in case-control

study, Oslo, Norway, 1998. Univariate, matched analysis.

Exposure Cases Controls Odds 95% conf.

ratio interval

Eaten at pizza restaurant 9/37 12/70 1.8 0.62 - 5.0

Eaten at party 10/36 9/74 3.2 0.97 - 11

Eaten foods from deli 23/37 42/74 1.2 0.56 - 2.7

Eaten unpeeled fruits 19/37 54/74 0.27 0.10 - 0.78

Close contact with a case 7/35 2/72 13 1.5 - 110

Drank >4 glas of water per day 21/37 33/74 1.7 0.73 - 3.9

Customer of water company B 27/37 33/74 4.0 1.3 - 7.3

Design of graphics

Think data-ink

Every bit of ink should have a reason

Designing graphics

• Show the data

• Use ink for the data

• Remove unnecessary ink

• Remove gimmicks

• No 3D

• Careful with colours

0102030405060708090

No.

of

case

s

B C Y W Unknown

Serogroup

Cases of meningococcal disease in Dublin by serogroup

Cases of meningococcal disease in Dublin by serogroup

0

10

20

30

40

50

60

70

80

90

B C Y W Unknown

Serogroup

No.

of

case

s

Cases of meningococcal disease in Dublin by serogroup

0

10

20

30

40

50

60

70

80

90

B C Y W Unknown

Serogroup

No.

of

case

s

Cases of meningococcal disease in Dublin by serogroup

0

20

40

60

80

B C Y W Unknown

Serogroup

No.

of

case

s