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36 terms

Ch 4 Vocab

STUDY
PLAY
population
the entire group of individuals about whiche we want information
sample
the part of the population from which we actually collect information
convenience sample
interviewr chooses individual who are easist to reach
bias
occurs when the design of a study systematicall favors certain outcomes
voluntary response sample
consists of people who choose themselves by responding to a general appeal
simple random sample (SRS)
is chosen so that every set of n individuals has an equal chance to be the sample actually selected
table of random units
a long string of digits 0,1,2,.......9 such that.
1. Each entry in the table is equally likely to be any of the 10 digits 0 through 9
2. The entries are independent of each other
stratified random sample
an SRS is chosen groups of similar individuals, called strata
cluster sample and clusters
the population into smaller groups which mirror characteristics of the population. then the SRS of the clusters is chosen. All individuals in the chosen clusters are included in the sample. Sometimes an SRS is chosen from each cluster rather than including all members of the cluster.
strata
are similar within, but different between.
clusters
are similar between, but different within.
inference
the process of drawing conclusions about a population on the basis of sample data
sampling frame
the list of individuals from the sample is drawn
undercoverage
occurs when some groups in the population are left out of the sampling process
nonresponse
occurs when a chosen individual can't be contaced or refuses to participate
response bias
a systemic pattern of incorrect responses in a sample survey
observational study
observes individuals and measures variables of interest
experiment
deliberately imposes some treatment on individuals to measure their responses
lurking variable
a variable that is not among the explanatory or response variables in a study but that may influence the response variable
confounding
occurs when two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other
treatment
specific condition applied to the individuals in an experiment
experimental units
the smallest collection of individuals to which treatments are applied
subjects
human experimental units
factors
explanatory variables
random assignment
experimental units are assigned to treatments using chance process
completely randomized design
the treatments are assigned to all the experimental units completely by chance
control group
provides a baseline for comparing the effects of the other treatments
replication
using enough experimental units to be sure that results did not happen by chance
placebo effect
the response to a dummy treatment
double blind study
neither the subjects nor those who interact with them and measure the response variable know which treatment each subject received
single blind study
the subjects are unaware of which treatment they are receiving, but the people interacting with them and measuring the response do know
statistically significant
an observed effect so large that it would rarely occur by chance
block
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
randomized block design
the random assignment of experimental units to treatments is carried out separately within each block
matched pairs design
blocks are created by matching pairs of similar experimental units
inference charts
were individuals randomly selected?