Biostatistics

Summarization Of Data

Summarization of qualitative data

• Proportions• Ratios• Rates

• Absolute numbers do not make sense • We have to relate them to another amount so

we can understand them

• Class one:– Number of females is 50

• Class two:– Number of females is 100

• Class one :– Total number is 100

• Class two:– Total number is 400

Proportion

• A proportion refers to the fraction of the total that possesses a certain attribute.

A percentage is another way of expressing a proportion. A percentage is equal to the proportion times 100.

• consists of one count as the numerator divided by another count as the denominator. – all the individuals in the numerator must also be included in the

denominator,

• Proportion of females in class one=50/100 = 0.5

• Percent of females in class one=50/100 X100 = 50%

• Proportion of females in class two=100/400 = 0.25%

• Percent of females in class two100/400 X 100 = 25%

Table No. () year of study, medical students, International university of Africa, 2011

Study of year Frequency Percent (relative frequency)

Cumulative frequency

First year 15026.8 26.8

Second year 13023.2 50

Third year 11019.6 69.6

Fourth year 9016.1 85.7

Fifth year 8014.3 100

Total 560100

Figure No. () year of study, medical students, International university of Africa, 2011

first year second year third year fourth year fifth year

26.80%

23.20%

19.60%

16.10%14.30%

Figure No. () gender distribution , medical students, International university of Africa, 2011

class one class two

50%

75%

50%

25%

males females

Figure No. () year of study, medical students, International university of Africa, 2011

27%

23%19%

16%

14%

first year second year third year fourth year fifth year

• Class one:– Number of females is 50– Number of males is 50

• Class two:– Number of females is 100 – Number of males is 300

Ratio

• A numerator divided by a denominator that usually does not include subjects of the numerator.

• A relation between two independent numbers

• Ratio of females to males in class one is:• 50/50 0r 50:50 =• 1/1 or 1:1

• Ratio of females to males in class two is:• 100/300 or 100:300 =• 1/3 or 1:3

• Village A total number of population = 500• number of all malaria cases in last month = 31• Number of new malaria cases in last month 30

• number of all tuberculosis cases in last month = 40

• Number of new cases of tuberculosis during last month = 2

• Number of new malaria cases in March =30

• Number of new malaria cases in September = 80

Rate

• The velocity of occurrence of an event per unit of time

• Numerator – denominator – unit of time

• Rate of malaria occurrence last month = 30/50 X100 per month

• = 60% per month

• Rate of TB occurrence last month = 2/500 X 100 per month

• = 0.4% per month