Chapter 9 & 10 (continued) Flashcards
Define: population
the entire group under study as defined by research objectives
Define: sample
a subset of the population that should represent the entire group
Define: sample unit
the basic level of investigation
define: census
an accounting of the complete population
define: sample frame
a master list of the sample units in the population
define: sample frame error
the degree to which the sample frame fails to account for all of the population
define: sampling error
any error in a survey that occurs because a sample is used
3 reasons to take a sample
- practicality (cost, time, population size.
- inability of researcher to analyze huge amounts of data from census
- samples can produce precise results
define: probability samples
ones in which members of the population have a known chance (probability) of being selected into the sample
define: nonprobability samples
instances in which the chances (probability) of selecting members from the population into the sample are unknown
What are the four probability sampling methods?
- simple random sampling
- systematic sampling
- cluster sampling
- stratified sampling
Define: simple random sampling
the probability of being selected into the sample is “known” and equal for all members of the population
What is the probability of selection for simple random sampling?
sample size/population size
What is the blind draw method or random device method?
the use of an apparatus of some sort to ensure that every member of the population has the same chance of being selected into the sample
Define: systematic sampling
way to select a random sample from a directory or list that is much more efficient than simple random sampling
what is a skip interval
determined by taking the size of your sampling frame (or population) and divided by the sample size needed
How does systematic sampling work?
randomly choose a start, pick a nth sample unit for study
define: cluster sampling
method in which the population is divided into groups, any of which can be considered a representative sample
cluster sampling is also called
area sampling
in cluster sampling, the population is divided into subgroups, called
clusters
Each cluster should represent the _____
population
True or false: Area sampling is a form of cluster sampling
true
What is area sampling?
the geographic area is divided into clusters
When the researcher knows the answers to the research question are likely to vary by subgroups, the sample may be divided into
strata
define: stratified sampling
method in which the population is separated into different strata and a sample is taken from each stratum
You assume responses to variables will vary across a population. The greater this variance, the _____ accurate your predictions/results become
less
If you can break up the population into smaller, more homogeneous groups, and measure the variable independent of each other, then _____ attributed to group differences can be accounted for
variance
The less variance in a group, the _____ sample size it takes to produce a precise answer
less
Why is stratified sampling more precise?
Allows the researcher to allocate more of the sample to strata with more variance and less of the sample to strata with less variance
True or false: nonprobability sampling methods are based on fairness, equity, or equal chance
False
What are the four nonprobability sampling methods?
convenience sampling, purposive sampling, referral sampling, quota sampling
Define: convenience samples
Samples drawn at the convenience of the interviewer
define: purposive samples
requires a judgment or an educated guess as to who should represent the sample
define: referral samples
require respondents to provide the names of prospective respondents
define: quota samples
specified percentages of the total sample for various types of individuals to be interviewed
define: online panels
large numbers of individuals who have agreed to participate in online suveys
define: river samples
created via the use of banners, pop-ups, or other online devices that invite website visitors to take part in the survey
define: email list samples
purchased or otherwise procured from someone or some company that has compiled email addresses of opt-in members of the population of interest
a sample size decision is usually a compromise between what is theoretically perfect and what is ________
practically feasible
Many practitioners have a large sample bias, which is…..
a false belief that sample size determines a sample’s representativeness
Is sampling method related to representativeness?
Yes, using a poor or sloppy method to collect data causes error and is only corrected by using a better method.
Only a _______ sample is truly representative of a population
probability sample
Sample size does help determine the
accuracy of findings
Define: sample accuracy
refers to how close a random sample’s statistic is to the true population’s value it represents
Define: nonsampling error
pertains to all sources of error other than sample selection method and sample size
Define: sampling error
involves sample selection and sample size
How many responses do you want for every item on a survey?
5 minimum
More sophisticated approaches take into account ________ which help you interpret results
confidence intervals
There is only one method of determining sample size that allows the researcher to predetermine the accuracy of the sample results….
confidence interval method of determining sample size
When thinking sample size, what three things should you balance?
level of confidence, variability, and amount of acceptable sample error
define: variability
refers to how similar or dissimilar responses are to a given question
The more important the decision, the ____ the sample error
smaller
The more important the decision, the more likely the manager will want ______ confidence
more
