Module #4 - Sampling Flashcards
What does a census measure?
the entire population
What does a sample measure?
Part of a population
Why does market research almost always rely on samples rather than censuses?
Censuses are too time-consuming and costly
When does using a census make sense?
When the population is small
True or False? A sample is always an estimate of the population
True
Does sampling error decrease or increase as sample size increases?
It decreases
Why is a sample not necessarily less accurate than a census?
Because both samples and censuses are subject to NON-SAMPLING error
What advantage does a sample have over a census?
A sample’s smaller relative size means that it is easier to control and minimize non-sampling errors than in a census.
What are the 5 steps of the sampling design process?
#1 - Define the population #2 - Determine the sampling frame #3 - Select sampling techniques #4 - Determine the sample size #5 - Execute the sampling process
Which step of the sampling design process is the most important?
Defining the target population
Why is defining the target population the most important step in the sampling design process?
Because having the right target population is crucial to answering the business question.
“It requires an understanding of the business issue and making sure that the selected sample relates appropriately to the business issue.”
What are some typical factors considered when defining the target population?
The same marketing factors usually considered, such as:
1) geographic areas
2) demographics
3) psychographics (attitudes, interests, beliefs)
Not sure about these last 2
4) Digital behavior data – recent/real-time data from search engines, recent web site visitors, etc.
5) business-to-business - business and organization firmographics (business type, size, etc)
What is the danger in defining a target population too narrowly?
Limiting the ability of the research to answer key business questions
What is the danger in defining a target population too broadly?
“Wasting” interviews and potential marketing programs on customers who are not likely to use their products/services
What is a “sampling frame”?
It is a list of all individuals from which the sample is (“to be”?) drawn.
How does a sample frame help in creating a sample?
It provides a cost effective and efficient method of contacting a representative sample of the target population
Why is the sampling frame often broader than the target population?
Rarely is a sampling frame a perfect fit for a target population. A broader frame allows for recruiters to use screeners qualify respondents.
What is synchrographic data?
“Real-time” data
What causes “sampling frame error”?
When the sampling frame is not a perfect representation of the target population
Give 3 examples of sampling frame error.
The frame excludes some members of the population.
The frame includes members who are NOT part of the population
The frame includes some members more than once.
What is “coverage” error?
It’s when the sampling frame does not include some members of the population.
How can you account for “coverage error”?
1) Redefine the target population
2) use weights or sampling methods to make the sample more representative of the target population.
What is RDD (Random Digit Dial)?
Proprietary software that starts with known area codes and exchanges, and then generates the last four or two digits.
What problems does RDD address?
People getting unlisted numbers, and having cells rather than land-lines
How can RDD samples be expensive?
They generate “bad” numbers as well as “good” ones.
What is a “targeted” list?
A list in which all households share a common characteristic, e.g., buying a certain product.
What is the main drawback of targeted lists?
The list may not be representative of the target population.
Which type of sample would researchers ideally use for 100% of their surveys? Probability or Non-probability?
Probability
What is a probability sample?
Probability samples are samples in which every unit in the population has a known probability of inclusion in the sample.
What is the main advantage of a probability sample?
It allows researchers to apply confidence intervals and to project out to a known population