biostatistics

1. Techniques for Data Presentation
Mohamed Hayir Tahlil Mohamud
MS in Biostatistics
May 11, 2021 1

2. Techniques of Data presentation
Data can be presented into:-
Array
Tabular
Graphical
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3. Array data presentation
• Array is listing the data values in order of
magnitude from the smallest to largest or vise
verse
• Array can be either
• Ascending: ordering data from smallest to
largest or
• Descending: ordering data from largest to
smallest.
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4. Example-1: arrange into array
• The following data shows list of ages of
participates in a study of smoking cessation
55 46 58 54 52 69
Ascending form: 46 52 54 55 58 69
Descending form: 69 58 55 54 52 46
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5. Tabular presentation
• A table s a format containing data in rows and
columns. Table makes data compact, concise,
and readily understandable without loosing
any information of interest.
Types of Tables
1. Univariate table
2. Bivariate table
3. Multivariate table
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6. Objectives of Tabulation
To clarify the object of investigation
To simplify complex data
To facilitate comparison
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7. Rules for tabulation
• The table should be simple and compact
• All title, subtitle, captions should be arranged in
systematic manner
• The unit of measurement should be clearly
defined in the table
• Table should be complete and self-explanatory
• A table should be attractive to draw attention o
readers
• Accurate process of presentation should be made
• Abbreviation should be avoided
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8. Expmle-2: suppose we have 20 adults with their
age and sex as given below
arrange this data into
a) Univarate tables
b) Bivariate table
F F F M M F M F F M F F F M F F M M M F
24 21 25 26 29 26 28 22 31 39 32 38 30 32 35 46 44 43 47 49
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9. Sex Frequency Percentage
Male 8 40
Female 12 60
Total 20 100
Univarate Table-1: Sex
Percentage = Frequency/Total*100
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10. Steps for building Frequency
distribution of Quantitate variable
i. step-1: Find the number of classes
ii. find the range
iii. Find class width
Class width= range/K
Range =largest value-smallest value
Number of class (K)=1+3.322(Log10n) or √n
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11. solution
Range =largest value-smallest value =49-
21=28
Number of class (K)=1+3.322(Log20)=5 or √n=
√20=5
Class width= range/K=28/5=6
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12. Age Frequency Percentage
21-26 6 30
27-32 6 30
33-38 2 10
39-44 3 15
45-50 3 15
Total 20 100
Univarate Table-2: Age
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13. Age Male Female Total
21-26 1 5 6
27-32 3 3 6
33-38 0 2 2
39-44 3 0 3
45-50 1 2 3
Total 8 12 20
Bivariate Table-1: Sex and Age
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14. Multivariate Table-3: Age, sex and
educational level
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Educational level__
Gender__
Age
Male Female
Total
Urban Rural Urban Rural
21-26 1 2 5 1 9
27-32 3 2 3 2 10
33-38 0 1 2 1 4
39-44 3 2 0 2 7
45-50 1 3 2 1 7
Total 8 10 12 7 37