Data, Distribution Introduction and Types - Biostatistics - Ravinandan A P.pdf

Data, Distribution Introduction and Types - Biostatistics - Ravinandan A P.pdf

1. Ravinandan A P
Assistant Professor
Sree Siddaganga College of Pharmacy in association with
Siddaganga Hospital, Tumkur-02

2. Types of Data
•Thetermvariablemeansaqualityorquantitywhichvaries
fromonememberofasampleorpopulationtoanother.
•Systolicbloodpressureisavariable,whichvariesbothfrom
persontoperson&frommeasurementtomeasurement
withinthesameperson.

3. •Sexisavariable,peoplebeingeithermaleorfemale.
•Thecollectionofobservationsormeasurementsona
variablecharacteristicdefinedontheunitsofa
populationorasampleselectedfromitarecalleddata.

4. •Itisusefultothinkofdataasbeingofseveraldifferenttypes,as
thetypeofdataisimportantindecidingwhichmethodsof
presentation&analysisweshouldadopt.
•Datacanbeoneoftwotypes:
•QualitativeData
•QuantitativeData

6. Qualitative Data:
•Qualitativedataarisewhenindividualsmayfallintoseparate
classes,suchasdiagnosisorsex.
•Aqualitativevariableisalsotermedacategoricalvariableor
aclassificationvariable.
•Qualitativedataarediscreteinnaturesuchasnumberof
deathsindifferentyears,populationofdifferenttowns,
personswithdifferentbloodgroupsinapopulation,&soon.

7. •Inlifesciences,suchstatisticsaremostlycollectedin
pharmacologytofindtheactionofadrug.
•Inclinicalpracticetotestorcomparetheefficacyofadrug,
vaccine,operationorlineoftreatment.
•Indemographytofindbirths,deaths,stillbirths,etc.
•Theresultsthusobtainedareexpressedasaratio,proportion,
percentileorarate.

8. Quantitative Data:
•Thesedatearenumerical,arisingfromcountsor
measurements.
•Woundareaisaquantitativevariable,asisthelength
oftimeuntilthewoundheals,&parity,thenumber
ofpreviouspregnancieswhichanexpectantmother
hashad.

9. •Ifthevaluesofthemeasurementscanonlytakeafew
separatevalues,oftenintegers,asdoesparity,those
dataaresaidtobediscrete.
•Ifthevaluesofthemeasurementscantakeanynumber
inarange,suchaswoundarea,height,orweight,the
dataaresaidtobecontinuous.

10. •Thequantitativedataobtainedfromcharacteristicvariableare
alsocalledcontinuousdataaseachindividualhasone
measurementfromacontinuousspectrumorrangesuchasbody
temperaturefrom35
0
Cto42
0
C,height150cmto180cm,pulse
ratefrom68perminuteto84perminuteandsoon.
•TheobservationsascendordescendfromOoranystartingpoint
intherangeorspectrum,suchasbloodpressureof100
individualsrisingfromlowest90mmofHgtothehighest150mm
ofHg.

11. Types of variables

12. Twokindsofvariables:
QualitativeorAttributeorCategoricalVariable:
Avariablethatcategorizesordescribesanelementofapopulation.
Note:Arithmeticoperations,suchasadditionandaveraging,arenot
meaningfulfordataresultingfromaqualitativevariable.

13. Secondkindofvariablesis:
Quantitative,orNumericalVariable:
Avariablethatquantifiesanelementofapopulation.
Note:Arithmeticoperationssuchasadditionandaveraging,are
meaningfulfordataresultingfromaquantitativevariable.

14. Qualitative variable:
•avariableorcharacteristicwhichcannotbemeasuredin
quantitativeformbutcanonlybeidentifiedbynameor
categories
•Forinstanceplaceofbirth,ethnicgroup,typeofdrug,stages
ofbreastcancer(I,II,III,orIV),degreeofpain(minimal,
moderate,severeorunbearable).

15. Quantitative variable:
•Aquantitativevariableisonethatcanbemeasured&expressed
numerically.
•Theycanbeoftwotypes:-DiscreteorContinuous.
•Thevaluesofadiscretevariableareusuallywholenumbers,such
asthenumberofepisodesofdiarrhoeainthefirstfiveyearsof
life.
•Acontinuousvariableisameasurementonacontinuousscale.
•Ex:weight,height,bloodpressure,age,etc.

16. Categorical variables
•orqualitative
•identifiesbasicdifferentiatingcharacteristicsof
thepopulation

17. Numerical variables
•orquantitative
•observationsormeasurementstakeonnumerical
values
•makessensetoaveragethesevalues
•twotypes-discrete&continuous

18. Discrete (numerical)
•listable set of values
•usually countsof items

19. Continuous (numerical)
•datacantakeonanyvaluesinthedomainof
thevariable
•usuallymeasurementsofsomething

20. NominalVariable:Aqualitativevariablethatcategorizes(ordescribes,ornames)
anelementofapopulation.
OrdinalVariable:Aqualitativevariablethatincorporatesanorderedposition,or
ranking.
DiscreteVariable:Aquantitativevariablethatcanassumeacountablenumberof
values.Intuitively,adiscretevariablecanassumevaluescorrespondingtoisolated
pointsalongalineinterval.Thatis,thereisagapbetweenanytwovalues.
ContinuousVariable:Aquantitativevariablethatcanassumeanuncountable
numberofvalues.Intuitively,acontinuousvariablecanassumeanyvaluealonga
lineinterval,includingeverypossiblevaluebetweenanytwovalues.

24. Nominal data
•Data that represent categories or names.
•There is no implied order to the categories of nominal data.
•In these types of data, individuals are simply placed in the proper
category or group, & the number in each category is counted.
•Each item must fit into exactly one category.
•Some other examples of nominal data:
✓Eye color -brown, black, etc.
✓Religion -Christianity, Islam, Hinduism, etc
✓Sex -male, female

28. Ordinal Data:-
•have order among the response classifications
•(categories). The spaces or intervals between the
categories are not necessarily equal.
•Example:
1. strongly agree
2. agree
3. no opinion
4. disagree
5. strongly disagree
•In the above situation, we only know that the data are
ordered.

29. Interval Data
•In interval data the intervals between values are the same.
•For ex, in the Fahrenheit temperature scale, the difference
between 70 degrees & 71 degrees is the same as the difference
between 32 and 33 degrees.
•But the scale is not a RATIO Scale.
•40 degrees Fahrenheit is not twice as much as 20 degrees
Fahrenheit.

30. Ratio Data
•Thedatavaluesinratiodatadohavemeaningfulratios
•Forex,ageisaratiodata,someonewhois40istwiceasoldas
someonewhois20.

31. Numerical continuous
•The scale with the greatest degree of quantification is a numerical
continuous scale.
•Each observation theoretically falls somewhere along a continuum.
•One is not restricted, in principle, to particular values such as the
integers of the discrete scale.
•The restricting factor is the degree of accuracy of the measuring
instrument most clinical measurements, such as blood pressure,
serum cholesterol level, height, weight, age etc. are on a numerical
continuous scale.

32. Classification by the number of variables
•Univariate-data that describes a single
characteristic of the population
•Bivariate-data that describes two characteristics of
the population
•Multivariate-data that describes more than two
characteristics (beyond the scope of this course

34. Identify the following variables:
1.the income of adults in your city
2.the color of M&M candies selected at random from a
bag
3.the number of speeding tickets each student in AP
Statistics has received
4.the area code of an individual
5.the birth weights of female babies born at a large
hospital over the course of a year
Numerical
Numerical
Numerical
Categorical
Categorical

35. Exercises
•Identify the type of data (nominal, ordinal, interval and ratio) represented by each of the
following. Confirm your answers by giving your own examples.
1. Blood group
2. Temperature (Celsius)
3. Ethnic group
4. Job satisfaction index (1-5)
5. Number of heart attacks
6. Calendar year
7. Serum uric acid (mg/100ml)
8. Number of accidents in 3 -year period
9. Number of cases of each reportable disease reported by a health worker
10. The average weight gain of 6 1-year old dogs (with a special diet supplement) was
950grams last month.

36. THANK
YOU