Intro to Data Collection
The entire group of individuals we want information about in a statistical study
What is population?
A sample that consists of individuals from the population who are easy to reach.
What is a convenience sample?
When some members of the population are less likely to be chosen or cannot be chosen for the sample.
What is undercoverage?
The fact that different random samples of the same size from the same population produce different estimates.
What is sampling variability?
When two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other.
What is confounding?
Experimental group whose primary purpose is to provide a baseline for comparing the effects of the other treatments. Depending on the purpose of the experiment, this group may be given an inactive treatment (placebo), an active treatment, or no treatment at all.
What is a control group?
A study that collects data from every individual in a population.
What is a census?
When a study is very likely to underestimate or very likely to overestimate the value you want to know.
What is bias?
When an individual chosen for the sample can't be contacted or refuses to participate.
What is nonresponse?
A sample chosen in such a way that every group of n individuals in the population has an equal chance to be selected as the sample.
What is a simple random sample (SRS)?
Specific condition applied to the individuals in an experiment. If an experiment has several explanatory variables, this is a combination of specific values of these variables.
What is a treatment?
A treatment that has no active ingredient but is otherwise like other treatments.
What is a placebo?
A subset of individuals in a population from which we collect data.
What is a sample?
A sample where people choose to be in the sample by responding to a general invitation?
What is a voluntary response sample?
When there is a consistent pattern or inaccurate responses to a survey question.
What is response bias?
1. Label,
2. Randomize,
3. Select
What are the steps to select a Simple Random Sample?
The object to which a treatment is randomly assigned.
What is an experimental unit?
Describes the fact that some subjects in an experiment will respond favorably to any treatment, even an inactive one.
What is the placebo effect?
A study that observes individuals and measures variables of interest, but does not attempt to influence the responses.
What is an observational study?
A sample where individuals are selected for the sample using a chance process.
What is a random sample?
The variable that measures an outcome of a study.
What is a response variable?
Design in which the experimental units are assigned to the treatments (or treatments to the experimental units) completely at random.
What is a completely randomized design?
Experimental units that are human beings or animals.
What is a subject?
An experiment in which either the subjects or the people who interact with them and measure the response don't know which treatment a subject is receiving.
What is single-blind?
A study that deliberately imposes treatments (conditions) on individuals to measure their responses.
What is an experiment?
An experimental design principle: use a chance process to assign experimental units to treatments (or treatments to experimental units). Doing so helps create roughly equivalent groups of experimental units by balancing the effects of other variables among the treatment groups.
What is random assignment?
A variable that may help predict or explain changes in a response variable.
What is an explanatory variable?
When the observed results of a study are too unusual to be explained by chance alone, the results are called statistically significant.
What is statistically significant?
*All planned studies must be reviewed in advance by an institutional review board charged with protecting the safety and well-being of the subjects.
*All individuals who are subjects in a study must give their informed consent before data are collected.
*All individual data must be kept confidential. Only statistical summaries for groups of subjects may be made public
What are the basic principles of Data Ethics?
An experiment in which neither the subjects nor those who interact with them and measure the response variable know which treatment a subject is receiving.
What is double-blind?