Data Presentation

1. Prof M A Hafez
Prof. & Advisor
Department of Biostatistics
Bangladesh University of Health Sciences (BUHS)

2. At the end of the session you should be able to:
 State importance of data presentation
 State different techniques of data Presentation;
 Prepare univariate and bivariate tables;
 Prepare appropriate graphs for:
- qualitative data
- quantitative data;

3.  Data collected and presented as it is, are called RAW data;
 These unsorted, unordered or untreated raw data fails to show
variations, patterns or the inherent message in the data set;
 Therefore, data need to be organized and presented in such a
way that they show patterns of variation clearly without loosing
any information of interest;
 Accurate methods of analysis can be decided upon only when
the characteristics of the data set are understood;

4. Frequency:
Frequency is the number of times an object, event
or characteristic occur;
Frequency distribution:
It is the organizing of a collection of observational/
numerical raw data into categories.

5.  Array
 Tabular
 Graphical
Array
Arranging in order
Family size: 4 6 8 2 9
Ascending: From lowest to highest
2 4 6 8 9
Descending: From highest to lowest
9 8 6 4 2

6. Method of summarizing data in rows and
columns :
into compact, concise and readily
understandable form.
without loosing any information of interest.

7. Presenting
 Univariate: one variable at a time.
 Bivariate: two variables at the same time.
 Multivariate: >2 variables at a time.
TYPES OF TABULAR PRESENTATION

8.  Suppose we have data of 20 adults aged from 20
to 49 years. There are 12 male and 8 female.

9. Table1 Gender distribution of 20 adults
Gender Number %
Male 12 60
Female 8 40
Total 20 100

10. Table 2 Age distribution of 20 adults
Age group
(yrs)
Number %
20-29 8 40
30-39 7 35
40-49 5 25
Total 20 100

11. Table 3 Gender distribution of 20 adults by age
group
Age group Male Female
20-29 5 3
30-39 5 2
40-49 2 3
Total 12 8

12. Advantages of tables
 A table helps organize information so it is easier to see
patterns and relationships.
 If a variable is continuous the table reveals a lot more
information.
 It may show the range, interval, and number of readings.

13. Why we use Graphical presentation ?
 Comprehension- Easy
 Visual presentation- Attractive
 Communication power - High

14. Data type
Table type
Univariate Bivariate
Qualitative • Simple Bar
• Component Bar
(Also called Proportional
Bar/Stack, Hundred percent bar)
• Pie diagram
• Line graph
Multiple Bar
Quantitative • Histogram
• Frequency Polygon
• Frequency Curve
• Ogive (Cumulative Frequency curve)
• Stem and leaf
• Box and whisker
Scattered
Diagram

15.  Used to present discrete or qualitative data.
 It includes separated bars of equal distance
across.
 The classification/categories of the variables are
usually placed on the X-axis and
 Y-axis usually represents the corresponding
frequency.

17. Table 4 percentage distribution of marking on tube-
well by level of arsenic (n=9,187 house holds)
*PPb = Parts Per billion
Figure 2 level of Arsenic in red, green and not marked
tube-well [Multiple bar chart]
Marki
ng on
tube-
well
Level of Arsenic
(PPb)*
Total
<50 50
% (n) % (n)
Red
45.2
(278)
54.8
(336)
100.0
(614)
Green
94.0
(2784)
6.0
(178)
100.0
(2962)
Not
marked
93.6
(5252)
6.4
(359)
100.0
(5611)
Total
90.5
(8314)
9.5
(873)
100.0
(9187)
0
10
20
30
40
50
60
70
80
90
100
Red Green Not marked
Percentage
Marking on tubewell
<50 >50

18. Table 5 EPI coverage survey on slums
of Dhaka
Figure 3 Percentage of EPI coverage survey
on slums of Dhaka [Proportional bar
chart/Hundred percent bar chart]
EPI coverage
Numb
er
Percent
age
Immunized 100 47
Partially
immunized
64 30
Not
immunized
49 23
Total 212 100 0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1
Not immunized
Partially immunized
Immunized

19.  It is commonly used graphical diagram for
presenting qualitative data.
 Shows the breakdown of a group or total in a
radius from.

20. Steps……
 1. draw a circle;
 2. divide the circle into sub– sets of the data corresponding
degrees of angle;
 3. compute the degree using formula:
degree=360*f/n
(f=freq. of a particular category, n = total frequency);
 The sectors are coloured or shaded in a different way.

21. Table 6 Distribution of patients visiting in
different diabetic hospital of Dhaka city in
a week
Figure 4 Distribution of patients visiting in
a week in different diabetic hospitals of
Dhaka city [Pie diagram]
Hospi
tal
A B C D Total
No of
patien
ts
1500 3660 1890 2575 9625
% of
patien
ts
16.0 37.0 20.0 27.0 100
Angle
1500X3
60/962
5
=56.1
3660X
360/9
625
=136.
9
1890X
360/9
625
=70.7
2575X
360/9
625
=96.3
360
16%
37%
27%
20%
A
B
C
D

22.  A line graph is used to present change over
time i.e trend.
 Line graph needs:
- Labeled X and Y axes
- Equal Intervals
- Data displayed by points connected
into lines

23. TABLE 7 DISTRIBUTION OF BED-SIDE TEMPERATURE
OF A PATIENT
FIGURE 5 DISTRIBUTION OF BED-SIDE
TEMPERATURE OF A PATIENT
(LINE GRAPH)
Time Temperature
6.00 AM 990F
9.00 AM 1040F
12.00 Noon 1050F
15.00 PM 1020F
18.00 PM 1010F
21.00 PM 1000F 96
97
98
99
100
101
102
103
104
105
106

24.  Graphical representation of the frequency
distribution of a quantitative variable.
 The variable of interest is placed on the x axis.
 A rectangle is drawn above each class interval with
its height corresponding to the interval’s
frequency, relative frequency, or percent
frequency.
 Unlike a bar graph, a histogram has no natural
separation between rectangles of next classes.

25. Table 8 Number of married couples by
their duration of marriage (in years)
Figure 6 Number of married couples by
their duration of marriage (in years)
[Histogram]
Duration of
marriage
(years)
Number of
married
couples
4-6 2
6-8 13
8-10 16
10-12 7
12-14 5
2
4
6
8
10
12
14
16
18
Number
of
married
couple
4 6 8 10 12 14

26. 2
4
6
8
10
12
14
16
18
Frequency
4 6 8 10 12 14

27.  An ogive is a graph of a cumulative frequency
distribution.
 It is obtained by plotting the cumulative frequencies of
a distribution against the upper class boundaries.
 The frequency of each class is plotted as a point.
 The plotted points are connected by directly lines.

28. Cost (Tk) Percent Frequency Cumulative frequency
50-60 4 4
60-70 26 30
70-80 32 62
80-90 14 76
90-100 14 90
100-110 10 100
Total 100

29. Figure 8 Ogive with Cumulative Percent Frequencies
Food Cost (Tk)
20
40
60
80
100
Cumulative
Percent
Frequency
50 60 70 80 90 100 110

30. It shows correlation between two
quantitative variables

31. TABLE 10 MONTHLY FAMILY INCOME AND WEIGHT OF
CHILDREN AGED 5 YEARS AND ABOVE
Monthly Family income
(Taka )
Weight (kg)
13000 15.5
20000 19.8
34500 21.5
24500 16.8
15500 12.6
30000 16.6
13000 18.1
8000 13.1
24500 20.1

32. 0
5
10
15
20
25
0 50 100 150 200 250 300 350 400
Monthly family income Taka ‘00
FIGURE 9 MONTHLY FAMILY INCOME AND WEIGHT OF CHILDREN 5
YEARS AND ABOVE [SCATTER DIAGRAM]

33. Importance of graphs
 They are attractive and impressive
 save time
 make data simple
 make comparison easy