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7/26/2019 Quant Methods
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QUANTITATIVERESEARCH METHODS
Irina Shklovski
7/26/2019 Quant Methods
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Quantitative Research
Methods Include a ide variet! o" la#orator! andnon$la#orator! %rocedures
Involve &easure&ent'
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Quantitative Research
Methods Measure&ent (o%ulations and Sa&%lin)
Rando& Assi)n&ent
*enerali+a#ilit!
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Quantitative Research
Methods Measure&ent (o%ulations and Sa&%lin)
Rando& Assi)n&ent
*enerali+a#ilit! Ti&e
Cross$sectional studies , sin)le e-%eri&ents
.on)itudinal studies , re%eated &easures
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Quantitative Research
Methods Method E-%eri&ents , Quasi$e-%eri&ents
/ehavioral Measures
Questionnaires , Surve!s Social Netork Anal!sis
Archival and Meta$Anal!sis
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0hat e ill talk a#out
toda! Measure&ent (o%ulation , Sa&%lin)
Rando& Assi)n&ent
*enerali+a#ilit!
Method
E-%eri&ents , Quasi$e-%eri&ents Questionnaires , Surve!s
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Measure&ent 1 Sa&%lin)
S%eci"! !our %o%ulation o" concern
Sa&%lin)
Selectin) res%ondents "ro& %o%ulation o"concern
Rando& sa&%lin)
S!ste&atic selection
Strati2ed sa&%lin)
Convenience sa&%lin)
Sno#all sa&%lin)
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Sa&%lin) /iases
Non$res%onse #ias /e %ersistent
O3er incentives and reards
Make it look i&%ortant
Volunteer #ias
So&e %eo%le volunteer relia#l! &ore thanothers "ora variet! o" tasks
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Rando& assi)n&ent
Di3erent "ro& rando& sa&%lin)
Mostl! used "or e-%eri&ents or 4ua+i$e-%eri&ents
(rotects a)ainst unsus%ected sources o" #ias
Does NOT )uarantee to #alance out thedi3erences #eteen %artici%ants
Chance is .UM(5
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*enerali+a#ilit!
Ho do !ou kno that hat !ou "ound in!our research stud! is6 in "act6 a )eneraltrend7
Does A reall!6 ala!s cause /7
I" A ha%%ens6 is / reall! as likel! toha%%en as !ou clai&7 Ala!s7 Under
certain conditions7
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Association vs8 Causalit!
Thanks to
Sara 9iesler"or these)ra%hs:
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E-%eri&ents , Quasi$e-%eri&ents
e-;%er;i;&ent (ronunciation< =ik$>s%er$?$&?nt also $>s%ir$= @unction< noun Et!&olo)!< Middle En)lish6 "ro& An)lo$@rench
es%eri&ent6 "ro& .atin e-%eri&entu&6 "ro& e-%eriri Date< Bth centur!
An o%eration or %rocedure carried out undercontrolled conditions to discover an unknone3ect or la6 to test or esta#lish a h!%othesis6or to illustrate a knon la
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E-%eri&ents , Quasi$e-%eri&ents 9e! "eature co&&on to all e-%eri&ents<
To deli#eratel! var! soðin) in order todiscover hat ha%%ens to soðin) else
later To seek the e3ects o" %resu&ed causes
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An E-%eri&ent is
A controlled e&%irical test o" a h!%othesis8
H!%otheses include<
A causes / A is #i))er6 "aster6 #etter than / A chan)es &ore than / hen e do
To re4uire&ents< Inde%endent varia#le that can #e &ani%ulated De%endent varia#le that can #e &easured
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E-%eri&ents in Research
Co&%arin) one desi)n or %rocess toanother
Decidin) on the i&%ortance o" a
%articular "eature in a user inter"ace Evaluatin) a technolo)! or a social
intervention in a controlled environ&ent
@indin) out hat reall! causes an e3ect @indin) out i" an e3ect reall! e-ists
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Re&e&#er
E-%eri&ents e-%lore the e3ects o" thin)sthat can #e MANIPULATED
#ut there is a caveat
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T!%es o" E-%eri&ents
Randomized 1 unitsF%artici%antsassi)ned to receive treat&ent oralternative condition rando&l!
Quazi 1 no rando& assi)n&ent Natural – contrastin) a naturall!
occurrin) event i8e8 disaster ith a
co&%arison condition
7/26/2019 Quant Methods
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I" !our stud! involvese-%eri&ents E-%eri&ental desi)n<
Shadish 08R86 Cook T8D8 , Ca&%#ell (8T8 GGExperimental and Quasi-Experimental Design forGeneralized Causal Inference8 /oston6 Mass<Hou)hton Miin
E-%eri&ental data anal!sis<
/runin)6 J8 .8 , 9int+6 /8 .8 KKL8 Computationalhandboo of statistics !"th ed#$8 Ne 5ork<.on)&an#
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Questionnaires , Surve!s
Sel"$re%ort &easures Questionnaires , surve!s
Intervies
Diaries T!%es
Structured
O%en$ended
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Questionnaires , Surve!s
Advanta)es Sa&%le lar)e %o%ulations chea% on
&aterials , e3ort
Ecientl! ask a lot o" 4uestions Disadvanta)es
Sel"$re%ort is "alli#le
Res%onse #iases are unavoida#le
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Res%onse #iases
Rel!in) on %eo%les &e&or! o" events ,#ehaviors E&otional states can %ri&eP &e&or!
Recenc! e3ects Routines are deceivin)
Social desira#ilit! Solution< none that are si&%le
5ea$sa!in) Solution< var! the direction o" res%onse
alternatives
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*eneral Surve! /iases
%ampling 1 are res%ondents re%resentativeo" %o%ulation o" interest7 Ho ere the!selected7
Co&erage 1 do all %ersons in the %o%ulationhave an e4ual chan)e o" )ettin) selected7
'easurement – 4uestion ordin) ,orderin) can o#struct inter%retation
Non-response 1 %eo%le ho res%ond di3er"ro& those that do not
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Desi)n is 9E5
(ormat 1 #ooklet6 %rinted vertical6 one$sided
Question ordering 1 earlier 4uestions can
%ri&e ansers to later 4uestions )age la*out 1 )rou% si&ilar ite&s , use
consistent "onts and res%onse cate)ories
)re-testing 1 conduct think$alouds ithvolunteers de&o)ra%hicall! si&ilar toe-%ected %artici%ants
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Co&&on (ro#le&s
Avoid co&%licated , dou#le$#arrel4uestions Co&%le-it! increases errors , non$res%onse
Navi)ation is %ara&ount 1 &ake sure thesurve! is EAS5 to "ollo
O%en$ended 4uestions The si+e o" the 2eld allotted ill deter&ine the
nu&#er o" ords Incentive is ke!
/UT a&ount di3erences have little i&%act
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I" !our stud! involvessurve!s Desi)nin) surve!s<
Dill&an6 D8 A86 S&!th6 J8 D86 , Christian6 .8 M8 GK8Internet+ mail+ and mixed-mode sur&e*s , the tailoreddesign method !rd ed#$# Ho#oken6 N8J8< 0ile! , Sons#
@oler6 @8 J8 KK8 Impro&ing sur&e* .uestions ,design and e&aluation# Thousand Oaks< Sa)e(u#lications#
Anal!+in) data<
Cohen6 J86 Cohen6 (86 0est6 S86 , Aiken6 .8 G8 /pplied multiple regression0correlation anal*sis forthe beha&ioral sciences !rd ed#$8 Mahah6 NJ<.arence Erl#au& Associates8
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So' hat7
Di3erence #eteen 4uantitative ðodsis in the 4uestions the! can anser
There are a .OT o" ðods and even&ore statistical techni4ues
Re)ardless o" the ðod6 i" its not ane-%eri&ent6 !ou CAN NOT %rove causation