introduction: statistics in geography module 02. reading read chapters 1 & 2read chapters 1...

Introduction:Introduction:Statistics in GeographyStatistics in Geography

module 02module 02

ReadingReading

• read Chapters 1 & 2read Chapters 1 & 2

Introduction:Introduction:Statistics in GeographyStatistics in Geography

Why Use Statistics?Why Use Statistics?

• help explainhelp explain• takes us beyond descriptiontakes us beyond description– idiographic vs nomotheticidiographic vs nomothetic• idiographicidiographic: relating to, involving or dealing : relating to, involving or dealing

with the individual or uniquewith the individual or unique• nomotheticnomothetic: formulating general statements or : formulating general statements or

scientific lawsscientific laws

• symbiotic relationship of the 2symbiotic relationship of the 2• nomothetic nomothetic ––>––> scientific method scientific method

Scientific MethodScientific Method

• modelmodel

• theorytheory

• laws & paradigmslaws & paradigms

Basic Terms & ConceptsBasic Terms & Concepts

• datadata

• data setdata set

• observationsobservations

• data valuedata value

Basic Terms & ConceptsBasic Terms & Concepts

• descriptivedescriptive– qualitativequalitative

• inferentialinferential– test hypothesestest hypotheses

– based on probabilities of outcomesbased on probabilities of outcomes

Basic Terms & ConceptsBasic Terms & Concepts

• statistical populationstatistical population

• samplesample

• estimationestimation

• hypothesis testinghypothesis testing

Levels of MeasurementLevels of Measurement

• nominalnominal

Levels of MeasurementLevels of Measurement

• nominalnominal

• ordinalordinal

Levels of MeasurementLevels of Measurement

• nominalnominal

• ordinalordinal

• intervalinterval

Levels of MeasurementLevels of Measurement

• nominalnominal

• ordinalordinal

• intervalinterval

• ratioratio

Levels of MeasurementLevels of Measurement

• nominalnominal least powerfulleast powerful

• ordinalordinal

• intervalinterval

• ratioratio

Levels of MeasurementLevels of Measurement

• nominalnominal

• ordinalordinal

• intervalinterval most powerfulmost powerful

• ratioratio

Levels of MeasurementLevels of Measurement

• nominalnominal least powerfulleast powerful

• ordinalordinal

• intervalinterval most powerfulmost powerful

• ratioratio

Levels of MeasurementLevels of Measurement

• nominalnominal least powerfulleast powerful

• ordinalordinal

• intervalinterval most powerfulmost powerful

• ratioratio

General Requirements for a General Requirements for a Statistical TestStatistical Test

• availabilityavailability

• reliabilityreliability

• sufficiencysufficiency

• definitiondefinition

Parametric Test or Parametric Test or Nonparametric Test?Nonparametric Test?

• parametricparametric–makes assumptionsmakes assumptions

• nonparametricnonparametric– no assumptionsno assumptions

Advantages of NonparametricAdvantages of Nonparametric

• distribution freedistribution free• works on ordinal works on ordinal (sometimes nominal)(sometimes nominal)

• easily computedeasily computed

• works on small samplesworks on small samples

• many are exact testsmany are exact tests

• generally easier to understandgenerally easier to understand

The Power of a TestThe Power of a Test

• so why use parametric?so why use parametric?–more powerfulmore powerful

• size of sample increases powersize of sample increases power

Huge Number of TestsHuge Number of Tests

• which one?which one?

• usually an easy selection processusually an easy selection process– based on nature of data, problem, based on nature of data, problem,

hypothesishypothesis

Geographic DataGeographic Data

Discussion of Geographic DataDiscussion of Geographic Data

• questionsquestions

• sourcessources

• methodmethod

• typetype

TypeType

• primaryprimary

• secondarysecondary

PrimaryPrimary

• fieldfield

• timetime

• sample designsample design

Secondary (Archival)Secondary (Archival)

• other usesother uses

• government or other government or other organizationorganization

• convenienceconvenience

• paper/CD/DVD/floppy/computer paper/CD/DVD/floppy/computer filefile

Advantages of SecondaryAdvantages of Secondary

• costcost

• timetime

• sample designsample design

Disadvantages of SecondaryDisadvantages of Secondary

• dependencedependence

• errorserrors