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What is a population?

• Complete group of entities that share common sets of characteristics• All that meet speci c conditions of membership• Population elements = those that meet population characteristics• Number of criteria increase = cost and time increase

De ning a population?

• Right population is selected based upon research questions researchdesign

• The target population must be er! clearl! de ned " through populationparameters

What is a sample?

•

Researches use samples to infer characteristics of populations #ithoutconsulting e er! member• A sample is a subset of a larger population• $ses a portion of the population to ma%e a conclusion regarding the #hole

population &representable'• Results of a good sample should ha e the same characteristcs as the

population as a #hole &generisable and replicable'

Wh! use samples?

• Practical reasons• Accurac! and reliabilit!

(ampling frames

• A list from #hich the sample is dra#n• Deri ed from population elements• )*g* customer databases+ member lists+ phone boo%s+ emplo!ees• No perfect frame e,ists " ma! need to de elop o#n sampling frame

(ampling procedures

•

Process of dra#ing the right sample• Di ided into non-probabilit! and probabilit! procedures• Necessar! for !our research proposal

Non-probabilit! sampling procedures

• Not e er population member has the opportunit! to be sampled• A correct sampling frame does not e,ist• Researchers #ho ma%e decisions on #ho the! #ill sample from+ #ith

limitaions• .ncludes/

- Con enience0eing included is a matter of con enience

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Right place at right time+ or eas! to access(uited to e,plorator! researchCannot necessaril! dra# important conclusions

- 1udgement2and-pic%ed b! researchers

Possess certain characteristics3a! be suitable procedure or in alidate results- (no#ball

Respondents to identif! and select other respondentsRelies on abilit! to locate initial set of respondents$seful for niche or other hard to reach population3a! lead to bias due to similarit! or familiarit!

- 4uota)nsures arious subgroups of a population is represented in aspeci c proportion5eft to the discretion of researcher

Digital and online easeRelies on in-depth sampling frame

Probabilit! sampling procedures

) er! population element is %no#n and has the opportunit! to be sampled(ampling error is reduced and more ob6ecti e.nferences can be made about the population+ theoreticall! #ithoutsampling error.ncludes/

- Random

)ach respondent has a %no#n and equal chance of beingselected) er! combination or population elements is a possibilit!)nsures sampling error is not added to b! the researchers

- (!stematicRandoml! selects the rst respondent " then de elop as!stem for subsequent sampling7nce the rst is selected+ all population elements no longerha e an equal chance)*g* e er! 89 th unique customer on a customer database

- (trati ed

0rea% population do#n into mutuall! e,clusi e strata &subgroups'+ then sample #ithin these strata

- Cluster