Secrets of Data Presentation April 14, 2011 Dr. Kenneth M. Coleman - - PowerPoint PPT Presentation

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Secrets of Data Presentation April 14, 2011 Dr. Kenneth M. Coleman - - PowerPoint PPT Presentation

The following slides are the property of their authors and are provided on this website as a public service. Please do not copy or redistribute these slides without the written permission of all of the listed authors. Secrets of Data


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The following slides are the property of their authors and are provided on this website as a public service. Please do not copy or redistribute these slides without the written permission of all of the listed authors.

Secrets of Data Presentation

April 14, 2011

  • Dr. Kenneth M. Coleman
  • Dr. Michael W. Traugott

University of Michigan ) mtrau@umich.edu (

Qatar University ~ SESRI ~ April Training Sessions

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THE ORGANIZATION OF DATA PRESENTATION

In any research report (published or supplied to a client), every table or figure should be able to stand alone.

Qatar University ~ SESRI ~ April Training Sessions

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That means the reader should be able to:

1) Understand what relationship was being investigated 2) Interpret what the results were 3) Come to the same conclusion that the researcher did. Was the hypothesis confirmed or disconfirmed?

Qatar University ~ SESRI ~ April Training Sessions

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THE SECRETS OF DATA PRESENTATION

  • 1. Identify where the data come from,

which variable is which, and what the nature of the relationship is. This enables the reader to reach the same conclusion as the author.

Qatar University ~ SESRI ~ April Training Sessions

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  • 2. As a matter of reference, every

presentation of data should be uniquely identified. Label cross-tabulations as Table 1, Table 2, etc. Label scatter plots and charts as Figure 1, Figure 2, etc. This convention tells the reader something about the kinds of data used

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A TABLE

  • 1. The title describes the contents

appropriately by variable. Identification of the Context: includes a reference to time or place, usually at the end of the title.

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A TABLE

Table 1. The Relationship between Sample Population and Preferred Mode of Interviewing

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A TABLE

  • 2. Identification of the Data Source: Could be

in the title or a footnote. Table 1. The Relationship between Sample Population and Preferred Mode of Interviewing, 2010 SESRI Omnibus Survey (Qatar).

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A TABLE

  • 3. Identify the independent variable (the

explanatory factor) and the dependent variable (the factor to be explained): Clearly label the rows and columns, by variable and category label

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A TABLE

  • 4. Calculate percentages across categories
  • f the independent variable.

Define row and column %'s to guide the reader: only put a “%” at the top of the column or at the left of a row, depending

  • n the direction of percentagizing.

Put “100%” at the bottom of the column or the end of the row Use the “N” notation to help as well

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A TABLE

  • 5. Give measures of association and results of

tests of statistical significance at the bottom

  • f the table or in footnotes associated with

the table.

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A TABLE

  • 6. Use other footnote conventions such as:

Test statistics and levels of significance Provide the full question wordings Indicate any special features or qualifiers

Qatar University ~ SESRI ~ April Training Sessions

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Table 1. The Relationship between Sample Population and Preferred Mode of Interviewing SAMPLE TYPE* PREFERRED MODE Qataris Expatriates Migrant Workers In person 79% 72% 89% By phone 5 9 2 Online survey 14 17 5 Don‟t know, refused 2 2 4 100% 100% 100% (662) (751) (682)

1 The question wording for Preferred Mode of Interview was “In politics

TODAY, do you consider yourself a Republican, Democrat, or Independent?” Sample Type was determined by the stratum from which the respondent was selected. * Differences in preferred mode of interviewing and sample type are significant at p <.01.

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A FIGURE

  • 1. Title describes the contents appropriately

by variable and contains the unique identifier. Identification of the Context: includes a reference to time or place, usually at the end

  • f the title.

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A FIGURE

Figure 1. The Relationship between Ideal Age for Boys and Girls to Get Married

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A FIGURE

  • 2. Identification of the Data Source: Could be

in the title or a footnote

Figure 1. The Relationship between the Perceived Ideal Age for Boys and Girls to Get Married, 2010 SESRI Omnibus Survey

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A FIGURE

  • 3. Use the axis convention:

Independent variable on the X or horizontal axis Dependent variable on the vertical or Y axis

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A FIGURE

  • 4. Label the axes to show the scales used.

Make the units of measurement clear: use a legend if necessary. Do not "break" either axis and distort the data.

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A FIGURE

  • 5. Give measures of association and

results of tests of statistical significance at the bottom of the figure or in footnotes there

Qatar University ~ SESRI ~ April Training Sessions

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KEY ELEMENTS OF A FIGURE

  • 6. Use other footnote conventions such as:

Give the full question wordings Indicate any special features or qualifiers

Qatar University ~ SESRI ~ April Training Sessions

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Qatar University ~ SESRI ~ April Training Sessions

r = .574, p < .001 Question wording is “In your opinion, what is the ideal age for boys/girls to get married?” 10 20 30 40 10 20 30 40

Ideal Age for Girls to Marry (in Years) Ideal Age for Boys to Marry (in years)

Figure 1. The Relationship between the Perceived Ideal Age for Boys/Girls to Get Married, 2010 SESRI Omnibus Survey

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What Does a Diagonal Line Contribute?

Qatar University ~ SESRI ~ April Training Sessions

r = .574, p < .001 Question wording is “In your opinion, what is the ideal age for boys/girls to get married?” 10 20 30 40 10 20 30 40

Ideal Age for Girls to Marry (in Years) Ideal Age for Boys to Marry (in years)

Figure 1. The Relationship between the Perceived Ideal Age for Boys/Girls to Get Married, 2010 SESRI Omnibus Survey

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FUNCTION OF GRAPHS and CHARTS

 Visual representation of quantities  Summarizing and interpreting quantitative

information

 Show patterns, trends, anomalies that may not

be immediately apparent in data tables

Qatar University ~ SESRI ~ April Training Sessions

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USING SCALES CORRECTLY

The most common problems with graphs and figures start with the inappropriate use of scales on the axes:

  • 1. No scale
  • 2. No origin (suppressed origin)
  • 3. Different scales to emphasize/minimize

change.

Qatar University ~ SESRI ~ April Training Sessions

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USING SCALES CORRECTLY

NO SCALE S A L E S

2007 2008 2009 2010

Year

Qatar University ~ SESRI ~ April Training Sessions

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USING SCALES CORRECTLY

WITH SCALE AND ORIGIN

($1,000,000)

S

40

A

30

L

20

E

10

S

2007

2008

2009 2010

Year

Qatar University ~ SESRI ~ April Training Sessions

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USING SCALES CORRECTLY

DIFFERENT SCALES SUGGEST DIFFERENT TRENDS

40

30 100 20 50 10

2006 2007 2008 2009 ‟06 ‟07 ‟08 „09

Qatar University ~ SESRI ~ April Training Sessions

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THE PROBLEM OF OBJECTS DISPLAYED IN 3 DIMENSIONS

 The media‟s frequent use of “objects” to

suggest different quantities

 They can confuse the relationships between

length, area, and volume

Qatar University ~ SESRI ~ April Training Sessions

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For length, the relationship should be easy: Twice as long is twice as much

Qatar University ~ SESRI ~ April Training Sessions

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THE PROBLEM OF OBJECTS DISPLAYED IN 3 DIMENSIONS

For area, it gets more complicated because twice as long and twice as high is 4 times the area:

Qatar University ~ SESRI ~ April Training Sessions

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THE PROBLEMS OF OBJECTS DISPLAYED IN 3 DIMENSIONS

For volume, doubling length, width and height makes 8 times the volume

Qatar University ~ SESRI ~ April Training Sessions

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THREE TYPES OF GRAPHS/ CHARTS

 Maps: Geographic distributions of values  Pie Charts: Show the proportion of “parts”

in relation to a “whole”

 Bar charts (vertical and horizontal): Used to

compare categories along a single measure by relative height/ length

Qatar University ~ SESRI ~ April Training Sessions

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EXAMPLE OF A MAP CHART

Qatar University ~ SESRI ~ April Training Sessions

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2008 ELECTORAL VOTE MAP

Qatar University ~ SESRI ~ April Training Sessions

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2008 PROPORTIONAL ELECTORAL VOTE MAP

Qatar University ~ SESRI ~ April Training Sessions

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ALTERING A MAP WITH REFERENCE TO A SPECIFIC TOPIC

Qatar University ~ SESRI ~ April Training Sessions

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REFERRING TO GEOGRAPHY WITHOUT ANY MAP

Qatar University ~ SESRI ~ April Training Sessions

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PRINCIPLES OF PIE CHARTS

Best suited to variables with a few categories, distinctly making up 100% of a total You can check by adding up the %‟s Permit comparison of categories as percent

  • f the total

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Pie Charts in Excel

  • 1. Run the frequencies for the selected variable in SPSS
  • 2. Transfer the necessary information (results) into an

Excel spreadsheet

  • 3. Select the appropriate Chart function in Excel after

highlighting the data series

  • 4. Work through the labeling of “slices” of the chart and

preparation of the title

  • 5. Copy the finished chart and paste it into a Word

document

  • 6. Save the Excel spreadsheet in case adjustments are

needed

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Pie Charts in Excel

We are interested in the presentation of attitudes about the sponsorship system or “kafala” (ATT10) The first step is to run the SPSS Frequencies

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Pie Charts in Excel

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Pie Charts in Excel

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Pie Charts in Excel

Qatar University ~ SESRI ~ April Training Sessions

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Qatar University ~ SESRI ~ April Training Sessions

44% 16% 31% 4% 5%

Should the Sponsorship System ("kafala") Be Changed?

Make workers more dependent Make workers less dependent Keep about the same Totally eliminate DK, Refused

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Qatar University ~ SESRI ~ April Training Sessions

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Qatar University ~ SESRI ~ April Training Sessions

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Including total as a category itself Categories listed do not comprise 100% of the total; they are only a few parts of the whole (other parts are not listed, left out of the chart)

COMMON PIE CHART MISTAKES

Qatar University ~ SESRI ~ April Training Sessions

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Yearly Sales

15% 20% 35% 1st Qtr 2nd Qtr 3rd Qtr

Qatar University ~ SESRI ~ April Training Sessions

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Problem?

Qatar University ~ SESRI ~ April Training Sessions

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Problem?

Qatar University ~ SESRI ~ April Training Sessions

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What‟s missing?

Qatar University ~ SESRI ~ April Training Sessions

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WHAT‟S WRONG WITH THIS CHART FROM FOX NEWS LAST OCTOBER?

Qatar University ~ SESRI ~ April Training Sessions

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PRINCIPLES OF BAR CHARTS

Bar charts are used to compare different categories along a single measure They can be very effective in displaying differences between groups They can also be misleading.

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Stacked Bar Charts in Excel

  • 1. Run the basic data in SPSS
  • 2. Transfer the necessary information (results) into an

Excel spreadsheet

  • 3. Select the appropriate Chart function in Excel after

highlighting the data series

  • 4. Work through the labeling of axes, definition of the

chart area, and preparation of the title

  • 5. Copy the finished chart and paste it into a Word

document

  • 6. Save the Excel spreadsheet in case adjustments are

needed

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Stacked Bar Charts in Excel

We are interested in the presentation of attitudes about the role of higher education of women (GEN06a – GEN06e) and how they differ by gender (HR06) The first step is to run the SPSS Crosstabs

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Stacked Bar Charts in Excel

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Stacked Bar Charts in Excel

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Stacked Bar Charts in Excel

Qatar University ~ SESRI ~ April Training Sessions

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How to Create Stacked Bar Charts in Excel

Qatar University ~ SESRI ~ April Training Sessions

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Qatar University ~ SESRI ~ April Training Sessions

29 35 37 64 20 32 40 42 77 28 20 40 60 80 100 Have a good husband Be a good wife Be a good mother Have a good career Have more freedom % Who Strongly Agree Higher Education Is Good for a Woman Because It Helps Her

Figure 1. Attitudes about The Role of Higher Education for Women, by Gender, 2010 SESRI Omnibus Survey

Men Women

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EXAMPLES OF GOOD BAR CHARTS

Qatar University ~ SESRI ~ April Training Sessions

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COMMON BAR CHART MISTAKES

“Breaking” the axis so that differences are distorted (maximized) Not paying strict attention to the scale so that “differences” are exaggerated

Qatar University ~ SESRI ~ April Training Sessions

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Qatar University ~ SESRI ~ April Training Sessions

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Qatar University ~ SESRI ~ April Training Sessions

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Qatar University ~ SESRI ~ April Training Sessions

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PROBLEMS WITH TITLES/ LABELS

Qatar University ~ SESRI ~ April Training Sessions

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PROBLEMS WITH TITLES/ LABELS

Qatar University ~ SESRI ~ April Training Sessions

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PROBLEMS WITH TITLES/ LABELS

Qatar University ~ SESRI ~ April Training Sessions

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SOMETIMES THE DATA ARE JUST WRONG!

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What Is a “Real Difference”?

Was either Bush or Gore really ahead? (Tracking polls with 500 respondents each day)

Qatar University ~ SESRI ~ April Training Sessions

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What‟s the Difference Between the Population Size and a Rate?

Qatar University ~ SESRI ~ April Training Sessions