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Unit 8: Presenting Data in 
Charts, Graphs and Tables 
#1-8-1
Warm Up Questions: Instructions 
 Take five minutes now to try the Unit 8 warm 
up questions in your manual. 
 Please do...
What You Will Learn 
 By the end of this unit you should be able to: 
 list the variables for analysing surveillance 
da...
 Person: Who develops a disease (for example, by 
age group or sex)? Are the distributions changing 
over time? 
 Place:...
Purpose of Displaying Data 
 The purpose of developing clearly 
understandable tables, charts and graphs is 
to facilitat...
Types of Variables 
 Categorical variables refer to items that can 
be grouped into categories. 
 Ordinal variables are ...
 Simpler is better. 
 Graphs, tables and charts can be used together. 
 Use clear descriptive titles and labels. 
 Pro...
 A diagram shown as a series of one or more 
points, lines, line segments, curves or areas 
 Represents variation of a v...
Scale Line Graph 
 Scale line graph: represents frequency 
distributions over time 
 Y-axis represents frequency. 
 X-a...
Example: Scale Line Graph 
Figure 8.1. Trends in HIV prevalence among 
pregnant women in Country X, years 1 – 10 
40 
30 
...
Specific Rules: Scale Line Graphs 
 Y-axis should be shorter than X-axis 
 Start the Y-axis with zero 
 Determine the r...
Bar Charts 
 Uses differently coloured or patterned bars to 
represent different classes 
 Y-axis represents frequency 
...
Example: Bar Chart 
Figure 8.2. Differences in HIV prevalence among 
various high-risk groups, Country X, year 1. 
30 
25 ...
Specific Rules: Bar Charts 
 Arrange categories that define bars in a natural 
order (for example, age). 
 If natural or...
Clustered Bar Charts 
 Bars can be presented as clusters of 
sub-groups in clustered bar charts. 
 These are useful to c...
Example: Clustered Bar Chart 
Figure 8.3. HIV prevalence rate among 
pregnant 15- to 19-year-olds at 4 clinic 
sites, City...
Specific Rules: 
Clustered Bar Charts 
 Show no more than three sub-bars within a 
group of bars. 
 Leave a space betwee...
Histograms 
 A representation of a frequency distribution 
by means of rectangles 
 Width of bars represents class inter...
Example: Histogram 
#1-8-19 
Figure 7.3. Children Living with HIV, 
Figure 8.4. Children living with HIV, 
District X, 200...
Pie Charts 
 A circular (360 degree) graphic 
representation 
 Compares subclasses or categories to the 
whole class or ...
#1-8-21 
Example: Pie Chart 
Figure 8.5. Projected annual expenditure 
requirements for HIV/AIDS care and support 
by 2005...
Area Maps 
 A graph used to plot variables by geographic 
locations 
#1-8-22
Example: Area Map 
Figure 8.6. HIV Prevalence in Adults 
in Africa, end 2003 
#1-8-23 
Source: UNAIDS, 2003
Tables 
#1-8-24 
 A rectangular arrangement of data in which 
the data are positioned in rows and columns. 
 Each row an...
#1-8-25 
Example: Table 
Table 8.1. Adults and children with HIV/AIDS 
by region in Country Y, end year X 
Region Adults a...
In Summary 
 Surveillance data can be analysed by person, 
place or time. 
 Depending on your data, you can choose 
from...
Warm Up Review 
 Take a few minutes now to look back at your 
answers to the warm up questions at the 
beginning of the u...
Answers to Warm Up Questions 
1. List two demographic variables by which 
surveillance data can be analysed. 
#1-8-28
Answers to Warm Up Questions, 
Cont. 
1. List two demographic variables by which 
surveillance data can be analysed. Age, ...
Answers to Warm Up Questions, 
Cont. 
2. True or false? Compiling all the data into one 
comprehensive chart or graph is m...
Answers to Warm Up Questions, 
Cont. 
2. True or false? Compiling all the data into one 
comprehensive chart or graph is m...
Answers to Warm Up Questions, 
Cont. 
3. Which of the following cannot be extracted 
from public health surveillance data:...
Answers to Warm Up Questions, 
Cont. 
3. Which of the following can not be extracted 
from public health surveillance data...
Answers to Warm Up Questions, 
Cont. 
4. Match the type of chart/graph with its 
example. 
#1-8-34
Answers to Warm Up Questions, 
Cont. 
4. Match the type of chart/graph with its 
example: 
scale line graph: d 
area map: ...
Small Group Discussion: 
Instructions 
 Get into small groups to discuss these 
questions. 
 Choose a speaker for your g...
Small Group Reports 
 Select one member from your group to 
present your answers. 
 Discuss with the rest of the class. ...
Case Study: Instructions 
 Try this case study individually. 
 We’ll discuss the answers in class. 
#1-8-38
Case Study Review 
 Follow along as we go over the case study in 
class. 
 Discuss your answers with the rest of the 
cl...
Questions, Process Check 
 Do you have any questions on the information 
we just covered? 
 Are you happy with how we wo...
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Unit 8 presenting data in charts, graphs and tables

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Unit 8 presenting data in charts, graphs and tables

  1. 1. Unit 8: Presenting Data in Charts, Graphs and Tables #1-8-1
  2. 2. Warm Up Questions: Instructions  Take five minutes now to try the Unit 8 warm up questions in your manual.  Please do not compare answers with other participants.  Your answers will not be collected or graded.  We will review your answers at the end of the unit. #1-8-2
  3. 3. What You Will Learn  By the end of this unit you should be able to:  list the variables for analysing surveillance data  identify the types of charts and graphs and when the use of each is appropriate #1-8-3
  4. 4.  Person: Who develops a disease (for example, by age group or sex)? Are the distributions changing over time?  Place: Where are cases occurring? Is the geographical distribution changing over time?  Time: Is the number of reported cases changing over time? #1-8-4 Analysing Surveillance Data
  5. 5. Purpose of Displaying Data  The purpose of developing clearly understandable tables, charts and graphs is to facilitate:  analysis of data  interpretation of data  effective, rapid communication on complex issues and situations #1-8-5
  6. 6. Types of Variables  Categorical variables refer to items that can be grouped into categories.  Ordinal variables are those that have a natural order.  Nominal variables represent discrete categories without a natural order.  Dichotomous variables have only two categories  Continuous variables are items that occur in numerical order. #1-8-6
  7. 7.  Simpler is better.  Graphs, tables and charts can be used together.  Use clear descriptive titles and labels.  Provide a narrative description of the highlights.  Don’t compare variables with different scales of magnitude. #1-8-7 General Rules for Displaying Data
  8. 8.  A diagram shown as a series of one or more points, lines, line segments, curves or areas  Represents variation of a variable in comparison with that of one or more other variables #1-8-8 Graphs
  9. 9. Scale Line Graph  Scale line graph: represents frequency distributions over time  Y-axis represents frequency.  X-axis represents time. #1-8-9
  10. 10. Example: Scale Line Graph Figure 8.1. Trends in HIV prevalence among pregnant women in Country X, years 1 – 10 40 30 20 10 0 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 % Source: STD/AIDS Control Programme, Uganda (2001) HIV/AIDS Surveillance Report #1-8-10 Year
  11. 11. Specific Rules: Scale Line Graphs  Y-axis should be shorter than X-axis  Start the Y-axis with zero  Determine the range of values needed  Select an interval size #1-8-11
  12. 12. Bar Charts  Uses differently coloured or patterned bars to represent different classes  Y-axis represents frequency  X-axis may represent time or different classes #1-8-12
  13. 13. Example: Bar Chart Figure 8.2. Differences in HIV prevalence among various high-risk groups, Country X, year 1. 30 25 20 15 10 5 0 Female sex workers Men who have sex with men Injecting drug users Prisoners Refugees Population % HIV prevalence #1-8-13
  14. 14. Specific Rules: Bar Charts  Arrange categories that define bars in a natural order (for example, age).  If natural order does not exist, define categories by name, such as country, sex or marital status.  Position the bars either vertically or horizontally.  Make bars the same width.  Length of bars should be proportional to the frequency of event. #1-8-14
  15. 15. Clustered Bar Charts  Bars can be presented as clusters of sub-groups in clustered bar charts.  These are useful to compare values across categories.  They are sometimes called stacked bar charts. #1-8-15
  16. 16. Example: Clustered Bar Chart Figure 8.3. HIV prevalence rate among pregnant 15- to 19-year-olds at 4 clinic sites, City X, Country Y, years 1 – 3 #1-8-16 35 30 25 20 15 10 5 0 Site 1 Site 2 Site 3 Site 4 Clinic Year 1 Year 2 Year 3 HIV prevalence (%) Source: Ministry of Health, Count ry Y. Annual AIDS Surveillance Report, year 3.
  17. 17. Specific Rules: Clustered Bar Charts  Show no more than three sub-bars within a group of bars.  Leave a space between adjacent groups of bars.  Use different colours or patterns to show different sub-groups for the variables being shown.  Include a legend that interprets the different colours and patterns. #1-8-17
  18. 18. Histograms  A representation of a frequency distribution by means of rectangles  Width of bars represents class intervals and height represents corresponding frequency #1-8-18
  19. 19. Example: Histogram #1-8-19 Figure 7.3. Children Living with HIV, Figure 8.4. Children living with HIV, District X, 2002 District X, 2002 160 140 120 100 80 60 40 20 0 <1 1 2 3 4 5 - 9 10 - 13
  20. 20. Pie Charts  A circular (360 degree) graphic representation  Compares subclasses or categories to the whole class or category using differently coloured or patterned segments #1-8-20
  21. 21. #1-8-21 Example: Pie Chart Figure 8.5. Projected annual expenditure requirements for HIV/AIDS care and support by 2005, by region
  22. 22. Area Maps  A graph used to plot variables by geographic locations #1-8-22
  23. 23. Example: Area Map Figure 8.6. HIV Prevalence in Adults in Africa, end 2003 #1-8-23 Source: UNAIDS, 2003
  24. 24. Tables #1-8-24  A rectangular arrangement of data in which the data are positioned in rows and columns.  Each row and column should be labelled.  Rows and columns with totals should be shown in the last row or in the right-hand column.
  25. 25. #1-8-25 Example: Table Table 8.1. Adults and children with HIV/AIDS by region in Country Y, end year X Region Adults and adolescents ≥ 15 years Children <15 years Total 1 14 800 200 15 000 2 400 000 20 000 420 000 3 997 000 3 000 1 000 000 4 985 000 15 000 1 000 000 5 1 460 000 40 000 1 500 000 6 465 000 35 000 500 000 7 940 000 10 000 950 000 8 380 000 220 000 600 000 9 900 000 600 000 1 500 000 10 545 000 5 000 550 000 Total 7 086 800 948 200 8 035 000
  26. 26. In Summary  Surveillance data can be analysed by person, place or time.  Depending on your data, you can choose from a variety of chart and graph formats, including pie charts, histograms, tables, etc.  Using several simpler graphics is more effective than attempting to combine all of the information into one figure. #1-8-26
  27. 27. Warm Up Review  Take a few minutes now to look back at your answers to the warm up questions at the beginning of the unit.  Make any changes you want to.  We will discuss the questions and answers in a few minutes. #1-8-27
  28. 28. Answers to Warm Up Questions 1. List two demographic variables by which surveillance data can be analysed. #1-8-28
  29. 29. Answers to Warm Up Questions, Cont. 1. List two demographic variables by which surveillance data can be analysed. Age, sex, marital status, etc. #1-8-29
  30. 30. Answers to Warm Up Questions, Cont. 2. True or false? Compiling all the data into one comprehensive chart or graph is more effective than including many simpler diagrams. #1-8-30
  31. 31. Answers to Warm Up Questions, Cont. 2. True or false? Compiling all the data into one comprehensive chart or graph is more effective than including many simpler diagrams. False #1-8-31
  32. 32. Answers to Warm Up Questions, Cont. 3. Which of the following cannot be extracted from public health surveillance data: a. changes over time b. changes by geographic distribution c. differences according to subject’s sex d. none of the above #1-8-32
  33. 33. Answers to Warm Up Questions, Cont. 3. Which of the following can not be extracted from public health surveillance data: a. changes over time b. changes by geographic distribution c. differences according to subject’s sex d. none of the above #1-8-33
  34. 34. Answers to Warm Up Questions, Cont. 4. Match the type of chart/graph with its example. #1-8-34
  35. 35. Answers to Warm Up Questions, Cont. 4. Match the type of chart/graph with its example: scale line graph: d area map: c pie chart: a histogram: b #1-8-35
  36. 36. Small Group Discussion: Instructions  Get into small groups to discuss these questions.  Choose a speaker for your group who will report back to the class. #1-8-36
  37. 37. Small Group Reports  Select one member from your group to present your answers.  Discuss with the rest of the class. #1-8-37
  38. 38. Case Study: Instructions  Try this case study individually.  We’ll discuss the answers in class. #1-8-38
  39. 39. Case Study Review  Follow along as we go over the case study in class.  Discuss your answers with the rest of the class. #1-8-39
  40. 40. Questions, Process Check  Do you have any questions on the information we just covered?  Are you happy with how we worked on Unit 8?  Do you want to try something different that will help the group? #1-8-40

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