# POL 2156 Study Guide - Quiz Guide: Stratified Sampling, Sampling Error, Sampling Frame

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22 Nov 2012
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QUIZ 2 NOTES – chapters 6, 7
Sampling
Three factors for idenfying a populaon to sample:
Unit of analysis (individual MPs)
Time period (1993-2000)
Ecient
Less expensive
Restricted to a certain meframe
Less data collecon/entry
Can provide accurate esmates within set parameters we are interested in the populaon,
sampling is a means to this end
Representaveness of the sample can be aected by:
Accuracy of the sampling frame
Sample size
The method by which the sample is chosen
Your sampling frame should minimize any ineciency/inaccuracy
Sample size: Larger sample sizes represent more accurately than smaller ones. To determine eecve
sample size we must look at:
The homogeneity of the sample – how similar a populaon is in regards to the variable of
interest. More homogenous, lower sample size.
The number of variables to study – the more complex our number of variables and relaonships,
the larger a sample size needed. Also, if looking at race specically we might need to skew our
samples in a way which doesn’t represent percentages in the actual populaon
The desired degree of accuracy – the researcher can state a margin of error they are willing to
accept
The method of random sampling used – Simple Random Sample, Straed Sample, Cluster
Sample
Simple Random Sampling:
All cases are listed and assigned numbers. Cases are then randomized (through a computer etc.)
unl proper sample is found
Less random/accurate version uses even intervals between cases to select sample group
Straed Sampling:
Breaks populaon into mutually exclusive subgroups and then randomly samples each
MP example could be broken up by party aliaon
Increases homogeneity and reduces sampling error, allows focus on small subgroups
Cluster Sampling:
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Divide the populaon into a number of subgroups, then randomly select from these subgroups and
select a few to randomly sample. Sampling error increases with every sample taken, larger sample size
can parally remedy this.
Sampling in Qualitave Research:
It is not possible and also not necessary to sample EVERYONE in order to get accurate ndings
qualitavely.
3 Common Sampling Methods in Qualitave Research:
Purposive – one of the most common strategies, parcipants are selected according to pre-
selected relevant criteria. Sample size depends on objecves, as well as me alloed. Oen
determined on the basis of “theorecal saturaon” – the point where no new info will be added
despite new parcipants. It is most successful when data review and analysis are done in
conjuncon with data collecon.
Quota somemes considered a type of Purposive sampling. We designate quotas for each
characterisc before selecng parcipants. This allows a focus on specic groups/issues to help
nd relevant informaon. Once quotas are selected, we nd people who t the criteria unl
quota is met.
Snowball – Parcipants use their social networks to refer the researcher to others who may t
the criteria to parcipate in the study. Oen used to nd and recruit “hidden populaons”
What is the dierence between Qual. And Quant. Sampling?
Name + Describe 2 types of sampling techniques used in Quantave research
Qualitave Research Methods:
Elite Interviews – “elite” refers to an individual or group with access to necessary specialized
informaon. In most cases, the size of this group is very small and hard to access. Random sampling
cannot be used, we must include as many members of the elite sample as possible.
Case Studies – Studying in-depth of a specic individual, program, or event. Can be useful to learn more
about a poorly-understood situaon, invesgang how an individual or program changes over me. We
cannot be sure it is generalizable, however.
Report layout:
Introducon - A raonal for studying the case & who they are and the riding they represent, etc.
Data Collecon - A descripon of the data you collected - websites, newspapers, etc. Time
period covered etc.
Paerns or Themes: A detailed descripon of the facts related to the case.
Subsecon A - Acvies in Riding
Subsecon B - Acvies in Parliament
Subsecon C - Acvies in Party if applicable
Subsecon D - Non-Polician Acvies - Volunteer & Acvism
Discussion - A discussion of the main paerns you found.
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