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Organizing data in tables and charts:
Criteria for effective presentation
Jane E. Miller, Ph.D.
Rutgers University
About the author
Author: The Chicago Guide to Writing about Multivariate Analysis (Chicago, 2005) and The Chicago Guide to Writing about Numbers (Chicago, 2004), and other articles about statistical literacy and quantitative communication.
Professor, Rutgers University Institute for Health, Health Care Policy and Aging
Research. Edward J. Bloustein School of Planning and Public
Policy.
Learning objectives
To learn the different types of variables and how they affect choices for organizing data.
To become aware of different principles for organizing variables in tables or charts.
To learn the strengths and weaknesses of tables, charts, and prose for organizing and conveying numeric information.
Performance objectives
To be able to choose among different criteria for organizing data for a particular task.
To be able to identify whether to use a table or chart to present data for a specific objective.
To understand how to write a prose description to coordinate with a table or chart.
Why does order of variables matter?
The arrangement of items in a table or chart should coordinate with order they are mentioned in the prose description. Avoid zigzagging back and forth across a chart or
among rows and columns of a table.
Usually describe a pattern based on observed numeric values, e.g., most to least common.
Often a hypothesis includes some theoretical basis of how items relate to one another.
Ordinal and continuous variables
Values of ordinal, interval, and ratio variables have an inherent numeric order. E.g., age groups, dates, blood pressure.
Numeric or chronological order of values is the principle for organizing those values in a table or chart.
Nominal variables
Values of nominal variables have no inherent numeric order. E.g., categories of race, gender, or region.
Need an organizing principle to determine sequence of items.
Same issue if you have >1 variable to present. Several different causes of death. Prevalence of >1 symptoms, attitudes, etc.
+ and - of different tools
Strengths Weaknesses Prose Easiest way to
explain patterns Hard to organize a
lot of numbers
Table Holds lots of #s Good for detail Predictable
structure
Harder to "see" patterns
Chart Holds lots of #s Easy to see
general patterns Predictable
structure
Difficult to see specific values
Complementary use of prose, tables & charts
Use tables and charts to present full set of numeric values.
Use prose to describe the pattern or address the hypothesis.
Use same ordering principle in table or chart and its accompanying prose. Improves clarity of narrative line.
Prose description of a pattern
Objectives: Describe size and shape of the pattern.Explain whether it matches hypothesis.
Specify direction and magnitude of association.Direction: “Which is higher?Magnitude: “How much higher?”
Direction for different types of variables
Direction for ordinal, interval or ratio variable: Is the relationship positive, negative, or level? E.g., as income rises, do death rates
increase, decrease or remain constant?For nominal variables:
Which category has the highest value? E.g., which gender has the higher death rate?
Principles for organizing data
Alphabetical orderOrder of items on original data collection
instrumentEmpirical orderTheoretical groupingsArbitrary order – NEVER a good idea!
Think about how the data will be used, and choose one of the above principles!
For tables and charts accompanied by prose
Pattern description
or hypothesis testing
Example: Attitudes about legal abortion
“Please tell me whether or not you think it should be possible for a pregnant woman to obtain a legal abortion”
% of respondents
who agree
If the woman wants it for any reason 43.7
If there is a strong chance of defect in the baby 79.8
If the woman's own health is seriously endangered by the pregnancy 88.2
If she is not married and does not want to marry the man 42.5
If she becomes pregnant as a result of rape 80.8
If she is married and does not want any more children 44.4
From the 2000 U.S. General Social Survey
Order of items from questionnaire
Agreement with legal abortion under specified circumstances, 2000 U.S. General Social Survey
0
20
40
60
80
100
Anyreason
Defect inbaby
Wants nomore kids
Mother'shealth
Pregnantdue torape
Notmarried
% o
f re
spo
nd
en
ts
Order of items from questionnaire
Agreement with legal abortion under specified circumstances, 2000 U.S. General Social Survey
0
20
40
60
80
100
Anyreason
Defect inbaby
Wants nomore kids
Mother'shealth
Pregnantdue torape
Notmarried
% o
f re
spo
nd
en
ts
Alphabetical order
Agreement with legal abortion under specified circumstances, 2000 U.S. General Social Survey
0
20
40
60
80
100
Anyreason
Defect inbaby
Mother'shealth
Notmarried
Rape Wants nomore
% o
f re
spon
dent
s
Empirical order (descending)
Agreement with legal abortion under specified circumstances, 2000 U.S. General Social Survey
0
20
40
60
80
100
Mother'shealth
Rape Defect inbaby
Wants nomore
Anyreason
Notmarried
% o
f re
spon
dent
s
Theoretical groupingAgreement with legal abortion under specified
circumstances, 2000 U.S. General Social Survey
0
20
40
60
80
100
Mother'shealth*
Pregnantdue torape*
Defect inbaby*
Wants nomorekids
Anyreason
Notmarried
% o
f resp
ondents
Health reasons Social reasons
Theoretical groupingAgreement with legal abortion under specified
circumstances, 2000 U.S. General Social Survey
0
20
40
60
80
100
Mother'shealth*
Pregnantdue torape*
Defect inbaby*
Wants nomorekids
Anyreason
Notmarried
% o
f re
spo
nd
en
ts
Health reasons Social reasons
Combining theoretical & empirical criteria
Descending dollar value of expenditures for necessities and non-necessities,
2002 U.S. Consumer Expenditure Survey
$-
$3,000
$6,000
$9,000
$12,000
$15,000
Necessities Non-necessities
Pattern with a third variableAgreement with legal abortion, by gender of respondent and circumstances of abortion, 2000 U.S. General Social Survey
Organized by topic of abortion question
0
20
40
60
80
100
Mother'shealth*
Pregnantdue torape*
Defect inbaby*
Wantsno more
kids
Anyreason
Notmarried
% o
f res
pond
ents Men
Women
Health reasons Social reasons
* difference between men and women is statistically significant at p<.05
Pattern with a third variableAgreement with legal abortion, by gender of respondent and circumstances of abortion, 2000 U.S. General Social Survey
Organized by topic of abortion question
0
20
40
60
80
100
Mother'shealth*
Pregnantdue torape*
Defect inbaby*
Wantsno more
kids
Anyreason
Notmarried
% o
f res
pond
ents Men
Women
Health reasons Social reasons
* difference between men and women is statistically significant at p<.05
Identifying theoretical criteria
Consult the published literature on your topic to learn about theoretical criteria for organizing your variables.
In new research areas, empirical sorting may yield clusters with similar response patterns that can then be explored for conceptual overlap.
For self-guided data lookupWhy is it important? When is it used?
Researchers look up data for own research questions, then organize the data using empirical or theoretical criteria.
How to organize data for such tasks? Alphabetical order Order of items from data collection instrument Standard ordering used in periodic reports
Alphabetical order
Widely familiar principle, e.g., used inPhone bookDaily stock market report
Learned at an early ageFacilitates self-guided lookup
Ordering for a public data source
Order of items on original data collection instrumentUsers can refer to codebookEasy to find the variables they need
Ordering used in periodic reportsStandardized from year to year for a given
topic
Summary
There is no one principle for organizing numeric data that fits all possible tasks.
Determine your main objectiveHypothesis testing or pattern descriptionData reporting for others’ use
Choose the organizing principle accordingly.
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