Chapter 6 Flashcards
Sample survey
sample people from a population and
interview them.
General Social Survey: use personal interviews of a random
sample of subjects from US adult population
Gallup Poll: use telephone interviews with random digit dialing
Observational Studies
observe subjects without any experimental
manipulation
Population
the people about whom we would
like to make generalizations
Sampling Frame
The roster or list from which we select
prospective participants to approach
Generalizing
The process of making an inference that the results
observed in a sample would hold in the population of
interest – if such an inference or conclusion is valid we can
say that it has generalizability
External Validity
The degree to which the conclusions in your study would
hold for other persons in other places and at other times
Randomization
the mechanism for achieving good sample
representation
“n”
notation for sample size
Simple Random Sample
A method of sampling that involves
drawing a sample from a population so that every possible sample
has an equal probability of being selected
Probability Sampling
a truly random draw from a population
will resemble the population not only on known
characteristics, but unknown ones as well
Stratified Random Sampling
method of sampling from a population which can be partitioned into sub-populations
Systematic Random Sampling
method of selecting a sample from a larger population by choosing a random starting point and then selecting every k-th element at regular intervals
Cluster/Area Random Sampling
the random sampling method that requires selecting samples based on a system of intervals in a numbered population
Sampling Error
statistical characteristics of a population are estimated from a subset, or sample, of that population.
Probability Proportionate to Size ( PPS)
If sampling units vary in size, may not want to
make them equally likely to be selected
NonProbability Sampling
a method of selecting units from a population using a subjective (i.e. non-random) method
Voluntary Sampling
subjects volunteer for the sample, but the sample
poorly represent the population and yield misleading conclusions
e.g., polls on the Internet, and polls on TV news
Selection Bias
subjects self-select into the sample
e.g. viewers who respond tend to be those who can easily access the
internet and feel strongly enough about the issue
Convenience Sampling
It consists of surveying whoever happens to
be around, or who is willing to respond.
– This may lead the results to be wildly astray
Purposive/Judgement Sampling
A strategy that seeks out participants with particular characteristics,
according to the needs of the developing analysis and emerging theory
Snowball Sampling
From an initial ‘seed’ of respondents, collect contact
information for other possible respondents.
* Recent variation: respondent-driven sampling
Quota Sampling
Based on known characteristics of the population, develop
quotas for people with different characteristics of interest.
* Within each group, recruit subjects until the quota is filled.
* Generally to be avoided
