Ch. 4 test Flashcards
The (blank) in a statistical study is the entire group of individuals we want information about. For example, all registered voters in a given county.
population
A (blank) is a subset of individuals in the population from which we actually collect data.
sample
A (blank) collects data from every individual in the population.
census
The design of a (blank) shows bias if it would consistently underestimate or consistently overestimate the value you want to know.
statistical study
A sample that chooses the individuals easiest to reach. This will typically result in a
biased sample of like-minded individuals.
convenience sample
A sample that consists of people who choose themselves by responding to a general invitation. shows bias because people with strong opinions (often in the same direction) are most likely to respond.
Voluntary response samples
A (blank) sample of size n consists of n individuals from the population chosen
in such a way that every set of n individuals has an equal chance to be the sample actually
selected.
simple random sample (SRS)
A table of (blank) is a long string of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 with these two properties:
- Each entry in the table is equally likely to be any of the 10 digits 0 through 9.
- The entries are independent of each other. That is, knowledge of one part of the table
gives no information about any other part.
random digits
choose an SRS in two steps:
Step 1: Label. Assign a numerical label to every individual in the population.
Step 2: Table. Use Table B to select labels at random.
To get a stratified random sample, start by…
1) Classifying the population into groups of similar
individuals, called strata.
2) Then choose a separate SRS in each stratum and combine these SRSs to form the sample.
To get a cluster sample, start by…
1) Classifying the population into groups of individuals that are
located near each other, called clusters.
2) Then choose an SRS of the clusters. All individuals in the chosen clusters are included in the sample.
(Blank) occurs when some members of the population cannot be chosen in a sample.
Undercoverage
(blank) occurs when an individual chosen for the sample can’t be contacted or refuses to participate.
Nonresponse
A systematic pattern of incorrect responses in a sample survey leads to (blank).
Response bias
The (blank) is the most important influence on the answers given to a sample survey.
wording of questions
An (blank) observes individuals and measures variables of interest but does not attempt to influence the responses.
observational study
An (blank) deliberately imposes some treatment on individuals to measure their responses.
experiment
(Blank) occurs when two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other. Observational studies often fail to provide valid causal links between variables due to confounding
Confounding
A specific condition applied to the individuals in an experiment is called a (blank). If an experiment has several explanatory variables, a (blank) is a combination of specific values of these variables.
Treatment
The (blank) are the smallest collection of individuals to which treatments are applied.
experimental units
When the experimental units are human beings, they often are called (blank).
subjects
4 basic principles for designing experiments
- Comparison.
- Random assignment
- Control
- Replication
An observed effect so large that it would rarely occur by chance is called (blank).
statistically significant
A statistically significant association in data from a well-designed experiment does imply
causation.
True
In a (blank), the treatments are assigned to all the experimental
units completely by chance.
completely randomized design
Some experiments may include a (blank) that receives an inactive treatment or an existing baseline treatment.
control group
The response to a dummy treatment is called the (blank).
placebo effect
In a (blank), neither the subjects nor those who interact with them and
measure the response variable know which treatment a subject received.
double-blind experiment
A (blank) is a group of experimental units that are known before the experiment to be similar in
some way that is expected to affect the response to the treatments.
block
In a (blank), the random assignment of experimental units to treatments is carried out separately within each block.
randomized block design
A (blank) is a randomized blocked experiment in which each block
consists of a matching pair of similar experimental units.
matched pairs design
