BIOSTATISTICS

BIOSTATISTICS

STATISTICSIt is the science of collection, summarizing , analyzing ,interpreting & presentation of data.

BIOSTATISTICSBIOSTATISTICS

--Branch of statisticsBranch of statistics-Deals with the application of -Deals with the application of statistical methodsstatistical methodsto the information related to to the information related to Health sciences.Health sciences.

TYPES:

1. DESCRIPTIVE BIOSTATISTICS deal with the enumeration, organization And graphical representation of data.

2. INFERENTIAL BIOSTATISTICS.

are concerned with reaching conclusions

from incomplete information,

that is, generalizing from the specific sample.

VARIABLE :VARIABLE :

It is the characteristic of the It is the characteristic of the person,person,object object

or phenomenonor phenomenon that can take on any value. that can take on any value.

DATA:DATA:

It is the It is the set of valuesset of values of one or more variables of one or more variables recorded onrecorded on

one or more individuals. one or more individuals.

Primary Data:Primary Data:Census is an example ofCensus is an example of

collecting primary data from collecting primary data from populationpopulation

Secondary Data:Secondary Data:Already existing data about problem / Already existing data about problem /

populationpopulationexampleexample from hospital record, to use the from hospital record, to use the census data.census data.

TYPES OF DATATYPES OF DATA

1. 1. QUALITATIVE DATAQUALITATIVE DATA : :

It is the data which shows It is the data which shows individual values falling into separate individual values falling into separate

classes,classes,

these classes may have no numerical these classes may have no numerical relationship with one another.relationship with one another.

Example:Example:

hair color , severity of disease. hair color , severity of disease.

QUALITATIVE DATAQUALITATIVE DATA

A. NOMINAL DATAA. NOMINAL DATA

It is the data that It is the data that one can name, it is one can name, it is unordered, either-unordered, either-on type of data.on type of data.

Example:Example:

Sex Sex (Male, Female)(Male, Female)

hair color.hair color.

B. ORDINAL B. ORDINAL DATA ORDERED DATA ORDERED OR CATEGORICALOR CATEGORICALIt is the data in It is the data in which there is which there is natural ordering of natural ordering of the categories.the categories.

Example:Example: severity of severity of disease disease (Mild, Moderate, (Mild, Moderate,

severe),severe), occupational occupational groupsgroups

2. 2. QUANTITATIVE DATAQUANTITATIVE DATA : :

It is the data which It is the data which shows some numerical shows some numerical

value.value.

Example:Example:Family size , height , Family size , height ,

weight.weight.

QUANTITATIVE DATAQUANTITATIVE DATAA. DISCRETE QUANTITATIVE DATA

It is the quantitative data that takes

only integral (whole number) of values.

Example: Number of children in family,

Number of deaths.

B. CONTINUOUS QUANTITATIVE DATA

It is the quantitative data that can be recorded on continuous scale i,e it can take decimal value, too. Example: Height, weight ,hemoglobin

level.

Sources of data on community healthSources of data on community health Data may come from different sources:

Surveillance systems (e.g., NIH)

Planned surveys (Government, Universities, NGOs)

Experiments (Pharmaceutical Companies)

Health Organizations (Administrative Data sets)

Private sector (Banks, Companies, etc) Government (All government agencies)

Census:Census: (periodic count, after every 10 ys:)(periodic count, after every 10 ys:) There are 2 principal methods for There are 2 principal methods for Enumeration of population.Enumeration of population.

De facto:De facto: Which allocates persons according to their location at the time of Which allocates persons according to their location at the time of

enumeration.enumeration.and the total of and the total of all persons present at the time of the Censusall persons present at the time of the Census as the as the de de

factofacto population or population or persons �present in the area� on Census persons �present in the area� on Census DayDay

De jure:De jure: this assigns them according to their usual place of residencethis assigns them according to their usual place of residence((The total of The total of all usual residentsall usual residents is is generally referred to as the generally referred to as the de jurede jure

populationpopulation

Organizing DataOrganizing Data

Frequency Table Frequency Histogram Relative Frequency Histogram Frequency polygon Relative Frequency polygon Bar chart Pie chart stem-and-leaf display Box Plot

PRESENTATION OF DATAPRESENTATION OF DATA

RATES,RATIOS AND PROPORTIONS.RATES,RATIOS AND PROPORTIONS.

FREQUENCY DISTRIBUTION TABLES:FREQUENCY DISTRIBUTION TABLES:

- Simple Tables.- Simple Tables.

- Complex Tables.- Complex Tables.

- 2 x 2 Tables.- 2 x 2 Tables.

CHARTS AND GRAPHS.CHARTS AND GRAPHS.

RATERATE

A RATE IS DEFINED AS THE NUMBER OF A RATE IS DEFINED AS THE NUMBER OF EVENTSEVENTS

PER UNIT OF POP ; PARTICULAR TIME PER UNIT OF POP ; PARTICULAR TIME PERIOD.PERIOD.

RATE= (A/A+B) x RATE= (A/A+B) x TO CALCULATE A RATE,WE NEED THE TO CALCULATE A RATE,WE NEED THE

FOLLOWING:FOLLOWING: 1. 1. NUMERATORNUMERATOR i.e. THE No: OF EVENTS i.e. THE No: OF EVENTS OCCURINGIN A DEFINED PERIOD.OCCURINGIN A DEFINED PERIOD. 2. 2. DENOMINATORDENOMINATOR i.e. THE DEFINED i.e. THE DEFINED POPULATION.POPULATION. 3. 3. DEFINED PERIOD OF TIMEDEFINED PERIOD OF TIME 4. 4. A MULTIPLIER.A MULTIPLIER.

A RATEA RATE MEASURES THE MEASURES THE OCCURANCE OF SOME OCCURANCE OF SOME

PARTICULAR EVENT IN A PARTICULAR EVENT IN A SPECIFIED POPULATION IN A SPECIFIED POPULATION IN A

DEFINED PERIOD OF TIME.DEFINED PERIOD OF TIME.

THE VARIOUS CATEGORIES OF RATE ARE:THE VARIOUS CATEGORIES OF RATE ARE:

1. CRUDE RATES1. CRUDE RATES2. SPECIFIED RATES2. SPECIFIED RATES

3. STANDARDIZED RATES.3. STANDARDIZED RATES.

RATIORATIO A RATIO IS THE EXPRESSION OF A RATIO IS THE EXPRESSION OF

RELATIONSHIP BETWEEN TWO RELATIONSHIP BETWEEN TWO RANDOM QUANTITIES. RANDOM QUANTITIES.

IT IS OBTAINED BY DIVIDING ONE IT IS OBTAINED BY DIVIDING ONE QUANTITY BY ANOTHER.QUANTITY BY ANOTHER.

EXAMPLE EXAMPLE : Male : Female Ratio,: Male : Female Ratio, Rural: Urban Ratio,Rural: Urban Ratio, Doctor : Patient Ratio,Doctor : Patient Ratio, RBC : WBC Ratio.RBC : WBC Ratio.

PROPORTIONPROPORTION

A PROPORTION IS THE NUMERICAL A PROPORTION IS THE NUMERICAL EXPRESSION OF A PART DIVIDED BY EXPRESSION OF A PART DIVIDED BY THE WHOLE.THE WHOLE.

IN A PROPORTION, THE NUMERICAL IS IN A PROPORTION, THE NUMERICAL IS THE PART OF THE DENOMINATOR.THE PART OF THE DENOMINATOR.

PROPORTION = APROPORTION = A A + BA + B

WHEN A PROPORTION IS MULTIPLIED WHEN A PROPORTION IS MULTIPLIED BY 100, IT IS CALLED A BY 100, IT IS CALLED A PERCENTAGE.PERCENTAGE.

Organizing DataOrganizing Data

Frequency Table Frequency Histogram Relative Frequency Histogram Frequency polygon Relative Frequency polygon Bar chart Pie chart stem-and-leaf display Box Plot

Presentation of statistical Presentation of statistical DataData

1.Tabulation Simple T Frequency distribution T 2. Charts & Diagrams 1. Bar charts a. simple bar chart b. Multiple bar chart c. component bar chart 3. Histogram Frequency polygon Line Diagram Scatter Diagram 3.Pie charts 4. Pictogram 5. statistical Maps

TabulationTabulation

Are devices for presenting dataAre devices for presenting data May be simple or complexMay be simple or complex Some principlesSome principles Table should be numbered (Tab:1 or 2 )Table should be numbered (Tab:1 or 2 ) TitleTitle Headings of column & rowsHeadings of column & rows Data alphabetically or geographicallyData alphabetically or geographically Not too largeNot too large FootnotesFootnotes

Table 1Table 1Population of some cities of Saudi Population of some cities of Saudi

ArabiaArabiaCity PopulationCity Population

Arar 240000Arar 240000

Sakaka 114000Sakaka 114000

Source: Wikipedia

Frequency distribution Table Data is first split up in to convenient group (class intervals) Data is first split up in to convenient group (class intervals)

& no: of items ( frequency) are in adjacent columns& no: of items ( frequency) are in adjacent columns

E.g:- 2 3 5 8 2 3 5 7 8 9 7 4 2 4 6 7 3 2 4 6 7 9E.g:- 2 3 5 8 2 3 5 7 8 9 7 4 2 4 6 7 3 2 4 6 7 9

Age group Age group FrequencyFrequency

0-4 //// //// 100-4 //// //// 10

5-9 //// //// // 125-9 //// //// // 12

Charts & DiagramsCharts & Diagrams

For simple statistical dataFor simple statistical data

Have a powerful impact on the imagination of the Have a powerful impact on the imagination of the peoplepeople

Especially in newspapers & magazines.Especially in newspapers & magazines.

Diagrams are better retained in mind than Diagrams are better retained in mind than statistical tables.statistical tables.

Bar chartsBar charts

Way of presenting a set of numbers by the Way of presenting a set of numbers by the length of a barlength of a bar

length of a bar is proportional to the length of a bar is proportional to the magnitude to be represented.magnitude to be represented.

Easy to prepareEasy to prepare

Values to be comparedValues to be compared

A, simple bars

Vertical or horizontal

Are separated by spaces

Multiple bar chart / compound bar chart

2 or more bars can be grouped together

Component bar chart

Divided in to 2 or more parts

Each part representing a certain item

& proportional to the magnitude of that particular item .

Histogram

Pictorial diagram of frequency distribution

Class intervals given on horizontal axis

& frequency along vertical axis

Joining the mid points of histograms blocks

Showing freq: distrib: of reading of fating sugar blood

Line Diagram

Show the trends of events with the passage of time

1970 80 2000

8 mil

6

4

2

Malaria cases in Africa

Pie chart

The areas of a circle are compared

The area of each segment depends upon the angle

Often % in the segments

Pictogram

Popular method of presenting data to the “man in the street”

Small pictures or symbol are used to present the data.

Dot Maps

When refer to geographic or administrative areas.

Shaded maps

When refer to geographic or administrative areas, according to suitability. Presenting data of varying size

Areas are shaded with different colors

Scatter diagrams

Shows relationship b/w 2 variables ( linear nature )

+ve correlation b/w stress & B.P

THE ENDTHE END

GOOD BYE

GGOOOOD D BBYYEE