Unit 4 (3) Vocab - Collecting Data Flashcards
Vocabulary terms describing sampling, bias, experiments, and studies.
What is stratified random sampling?
In a study, the target population gets split into groups (strata, stratum [singular]) containing subjects with shared characteristics relevant to the goals of the study. Within every strata, subjects are randomly selected for data collection.
This method gives more precise estimates of population values than SRS does.
What is simple random sampling (SRS)?
When an SRS is taken from a population, subjects within the population are randomly selected. Everyone in the population has an equal chance of being selected. There must not be replacement after each sampling.
What is cluster sampling?
In a study, the researcher randomly selects subsets (clusters) within the population and then takes a census of every cluster. The clusters are usually within close proximity.
Cluster sampling saves time and money since data is collected from samples that are close together.
What is an observational study?
An observational study is a study in which individuals are observed over time for data collection without trying to affect them like in an experiment.
What is the difference between a retrospective observational study and a prospective observational study?
Retrospective observational studies use or reassess data that already exists, while prospective observational studies collect new data from individuals.
What is an experiment?
An experiment is a procedure in which experimental subjects are assigned to treatments to test a hypothesis and analyze variables.
What is convenience sampling?
A convenience sample consists of individuals who are easy to reach. In most cases, people in these samples are not representative of the whole population.
What is a voluntary response sample?
A voluntary response sample consists of individuals who volunteer to join in response to an open invitation. In most cases, people in these samples are not representative of the whole population.
Define undercoverage
Undercoverage occurs when some members of the population are less likely to be chosen or can’t be chosen for a sample. This method can show bias if individuals less likely to be included differ in relevant ways from the other members of the population.
Define nonresponse
Nonresponse occurs when an individual chosen for a sample can’t be contacted or refuses to participate. This method can show bias if individuals who don’t respond differ in relevant ways from the other members of the population.
Define response bias
Response bias occurs when there is a consistent pattern of inaccurate responses to a survey question. This can be caused by the wording of a question, characteristics of the interviewer, lack of anonymity, or other factors.
What is bias? What does it cause?
Bias occurs when a study has been conducted to either underestimate or overestimate data values that you want to know. This can create false statistics and misinformation.
What is an explanatory variable? What is a response variable?
Explanatory variables can predict or explain changes in the response variable (independent/x variable), and response variables measure the outcome of a study (dependable/y variable).
What is confounding?
Two variables are confounded when their effects on a response variable can’t be distinguished from each other. Due to this, sometimes cause and effect can’t be established.
Define treatment
A treatment is a combination of levels and factors (explanatory variables) imposed onto experimental units in an experiment.