STAT 201 Chapter 4: Sample Surveys in the Real World
Once data is collected, what can you do to adjust for nonsampling errors?
Weight the responses (1 of the 2 ways)
ADVANTAGES of internet surveys?
-quick, easy, and cheap to conduct -most people have access to internet and results can easily be shared with other researchers/community
The margin of error covers random sampling error, but does not account for what?
non-sampling error & non-random sampling error (undercoverage, nonresponse, etc)
Sampling Errors
occur because we took a sample- this is why sample results are different from census results
What are 3 types of errors we worry about in sampling?
1) Sampling Errors 2) Random Sampling Errors 3) Non-Sampling Errors
What are 2 things we can do to deal with nonresponse?
1) substitute other households in the same neighborhood for the non-responders 2) use statistical methods to weight the responses
What is a cluster sample?
A cluster sample involves dividing the entire population into groups (clusters), randomly choosing some clusters, and then measuring all the individuals in the selected clusters
What is a stratified sample?
A stratified sample involves dividing the sampling frame into groups (strata) and then taking a simple random sample within each stratum
Good sample designs use _____ to select individuals from the population.
CHANCE If chance is used to select the sample, there is less opportunity for bias to occur
A student organization randomly selects 20 classes on a college campus for participation in their survey. Everyone in the chosen classes will be surveyed. This is an example of random _____ sampling.
CLUSTER classrooms are the clusters and entire clusters are chosen for the sample
_____ error can be present even in a census
NONSAMPLING sampling errors will not be present in a census
What is nonresponse?
Nonresponse is when we can't get data from some of our individuals. This could be because we aren't able to contact them or because they refuse to participate.
What is NOT an error related to the selection of the sample?
Nonsampling errors
Which type of error is included in the margin of error in a confidence statement?
Random Sampling Error
The margin of error in a confidence statement includes only ________ sampling error
The margin of error in a confidence statement includes only RANDOM sampling error.
What is a sampling frame?
The sampling frame is the list of all the individuals from which we will take our sample
What problems can occur with question wording?
The wording of questions can influence how participants respond to them. A researcher could ask the same question in two different ways and get two different responses from the same individual. This affects survey results.
What is undercoverage?
Undercoverage occurs when some individuals/groups in the population are left out of the process of choosing the sample. This means that some individuals/groups are not in the sampling frame.
Random Sampling Error
difference between the statistic and the parameter that is caused by taking a random sample
Non-sampling errors
errors not related to taking a sample- can happen in a census as well as a sample
DISADVANTAGES of internet surveys?
very vulnerable to voluntary response, nonresponse, and undercoverage
