Laying out the data Designing effective tables FETP India.

Laying out the data

Designing effective tables

FETP India

Competency to be gained from this lecture

Lay out data effectively in tables

Key areas

• Essential rules when arranging a table• Common tables in epidemiology

Communicating patterns and messages contained in your data

• Show the patterns inherent in the data• Focus attention on these patterns• Serve as a basis for narrative or

discussion• Lead observer to insight, discussion,

conclusions

Avoid visual puzzles in tables

• Poorly organized data• Series of complicated numbers• Important data obscured• Unnecessary frames, lines, coloring• Decoration

Basic table rules

Column headings

Data

Footnotes

Title

Row headings

Typical table layout with components

Making sure that a table is understandable without referral

to other material • Title

Person Time Place Any measurement found in all columns

• Row and column headings Content of the row or column Any modifier applied to all cells of a row or column Unit of measurement Abbreviations, if necessary

Basic table rules

Using footnotes in a table

• Clarify points of potential ambiguity• Explain all:

Abbreviations Symbols Codes

• Note exclusions • Mention data source if applicable

Basic table rules

*ASC Ehrenberg, J R Statis Soc A, 140(3):277-297, 1977

Suggestions for data arrangement in tables *

1. Round data to 2 meaningful figures2. Summarize rows and columns3. Compare numbers in columns 4. Arrange key data by magnitude5. Help the reader with easy table layout6. Align numbers by decimal

Basic table rules

Table with excessive number of meaningful figures

Factor Cases RateRate Ratio pa

None 27451 2.345 1.000 Refb

A 34211 3.433 1.464 0.1011

B 11002 5.661 2.414 0.0133

C 5643 6.001 2.559 0.0005

a. p-valueb. Reference exposure category

Up to five meaningful figures

Rate ratios difficult to compare

1. Round data to 2 meaningful figures

Basic table rules

Rounding data in a table to 2 meaningful figures

Factor

Cases(1000s

) RateRate ratio p

None 27 2.3 1.0 Ref*

C 34 3.4 1.5 >0.100

A 11 5.7 2.4 <0.050

B 06 6.0 2.6 <0.001

a. p-valueb. Reference exposure category

2 meaningful figures

Rate ratios easier to compare

1. Round data to 2 meaningful figures

Basic table rules

Year M FBoth Sexes

1973 500 99 600

1970 580 87 670

1968 460 89 550

1966 260 71 330

Mean 430 86 520

Summary of the columns

Summary of the rows

2. Summarize rows and columns

Summarizing rows and columns with totals, averages or other statistics

Basic table rules

Compare numbers in columns

23 42 34 109 87 42 27 98 114 75

Difficult to compare numbers in rows

23 42 34

109 87 42 27 98

114 75

1st improvement: Right-justify numbers

vertically 2327

34424275

87 98109

114

2nd improvement: Sort numbers

3. Compare numbers in columns

Basic table rules

Organize data by magnitude

Exposure

Cases(1000

s) RateRate ratio Pa

A 11 2.9 1.3 > 0.100

B 06 9.9 4.3 < 0.001

C 34 5.4 2.3 > 0.100

None 27 2.3 1.0 Refb

4. Arrange key data by magnitude

a. p-value

b. Reference exposure category Basic table rules

Organize data by magnitude

Exposure

Cases(1000s

) RateRate ratio pa

B 6 9.9 4.3 < 0.010

C 34 5.4 2.3 < 0.050

A 11 2.9 1.3 > 0.001

None 27 2.3 1.0 Refb

a. p-value

b. Reference exposure category

4. Arrange key data by magnitude

Basic table rules

YearBothsexes Male Female

1973 600 500 99

1970 670 580 87

1968 550 460 89

1966 330 260 71

Spaced out table layout: Comparisons difficult for the reader

5. Help the reader with easy table layout

Basic table rules

YearBothsexes Male Female

1973 600 500 99

1970 670 580 87

1968 550 460 89

1966 330 260 71


Drawing columns and rows close together facilitates comparisons

Basic table rules

Intervening statistics: Separated numbers are harder to compare

Rate per 1000

Year Male Female All

1993 83 78 80

2.3 2.2 1.9

1994 62 66 63

2.5 2.7 1.8

1995 58 54 56

2.1 2.0 1.7

1996 55 45 51

2.0 2.0 1.7


Basic table rules

Rate per 1000 (SE)

Year Male Female All

1993 83 (2.3) 78 (2.2) 80 (1.9)

1994 62 (2.5) 66 (2.7) 63 (1.8)

1995 58 (2.1) 54 (2.0) 56 (1.7)

1996 55 (2.0) 45 (2.0) 51 (1.7)

Moving and minimizing intervening numbers facilitates readability


Basic table rules

Rate per 1000a

Year M F All

1993 83 78 80

1994 62 66 63

1995 58 54 56

1996 55 45 51

a. Standard errors for all rates less than 5% of rate.

Remove intervening numbers entirely if consequence minimal


Basic table rules

Align columns by decimal

23 42 34

10.9 8.7 42 27 9.8 114 75

23.0 42.0 34.010.9 8.7

42.0 27.0

9.8 114.0

75.0

Keeping the zeros or not is a question of personal style

6. Align numbers by decimal

Basic table rules

Arranging common types of tables in epidemiology

• Text table• Line listing• Two variable table• Complex table• Cohort study• Case-control study

Common tables

Text table

Between July 1 and August 31, 72 cases occurred in three classes of school A.

Class Cases 1 23 2 31 3 18 No cases occurred in the six other classes.

a. Text table

Common tables

State Age1 Sex Days2 Dose

New York 02 M 03 1

California 03 M 03 1

Pennsylvania 06 M 03 1


Colorado 04 F 04 1


Kansas 02 F 05 1

Colorado 03 M 05 1

New York 03 F 05 1

North Carolina 04 F 05 1

Missouri 11 M 05 1

Pennsylvania 03 F 07 1

California 04 F 14 2



1. Age in months

* MMWR, 48 (27):577

2. Days from dose to symptom onset

Reported cases of intussusception among recipients of rotavirus

vaccine, by state, United States, 1998-1999*

b. Line listing

Common tables

New cases of primary and secondary syphilis by age group and sex, United States, 1989

Age group Cases (100’s)

(years) Male Female Total

14 0.4 1.9 2.3

15-19 17.4 27.9 44.3

20-24 51.4 53.9 100.3

25-29 53.4 42.9 96.3

30-34 55.4 31.9 86.3

35-44 50.4 19.9 69.3

45-54 21.4 49.9 26.3

55 11.4 13.9 13.3

Total 260.4 180.9 440.3

c. Two variable table

Common tables

Complex table

Children

Character Exp %(n=205)

Not exp%(n=8729) p

Gestational age (weeks) at birth

<25 5.8 14 0.04

25-29 18.0 19 NS

Birthweight (kg)

1.5 -- 15 .0 15 NS

2.5 -- 39 .0 43 NS

d. Complex table

Common tables

Exposed

% Yes No

Exposure Res. a % ARb ARb RRc (95% CId)

Type 1

Sub Type 1-A ( - )

Sub Type 1-B ( - )

Sub Type 1-C ( - )

Type 2 ( - )

Type 3 ( - )

Type 4:

a. Res. = Responded

c. RR = Risk Ratio

b. AR = Attack Rate – cases per ___

d. 95% CI = 95% confidence interval of the RR

e. Cohort study

Risk of ______ by exposure, among #### residents of Place, time

Common tables

Exposed

Exposure % AR a RR b 95% CI c

Type or Level 3

Type or Level 2

Type or Level 1

None or Level 0 1.0 Referent

b. RR = Risk Ratio

c. 95% CI = 95% confidence interval of the RR

a. AR = Attack Rate – cases per ___

Risk of ______ by exposure, among #### residents of Place, time

e. Cohort study (reference group)

Common tables

Exposed % (n) a

Exposure Cases Controls OR b 95% CI c

Type 1 (n) (n) ( – )

Sub Type 1-A (n) (n) ( – )

Sub Type 1-B (n) (n) ( – )

Sub Type 1-C (n) (n) ( – )

Type 2 (n) (n) ( – )

Type 3 (n) (n) ( – )

c. 95% CI = 95% confidence interval of the OR

a. n = subjects responding b. OR = Odds Ratio

Exposures (%) among ### cases and ### controls, Place, Time

f. Case control study

Common tables

Take home messages

• Design your table around the message that is contained in your data

• Refer to templates that apply to the table you are trying to design

Laying out the data Designing effective tables FETP India.

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