Upgrade to remove ads
Only $35.99/year

Stats - Chapter 4

Terms in this set (35)

population
entire groups of individuals we want information about
census
collects data from every individual in the population
sample
a subset of individuals in the population from which we collect data
convenience sample
choosing individuals from the population who are easy to reach
bias
when a statistical study consistently overestimates or underestimates the value you want to know
voluntary response sample
consists of people who choose themselves by responding to a general invitation
random sampling
involves using a chance process to determine which members of a population are included in the sample
simple random sample (SRS) of size n
a sample chosen in such a way that every group of n individuals in a population has an equal chance to be selected as the sample
stratified random sample
classify the population into groups of similar individuals, choose separate SRS in each group, combine SRS's
cluster sample
classify the population into groups that are located near (geographically) each other, choose SRS of clusters - all individuals in the chosen clusters are surveyed
probability sample
a sample chosen by chance gives each member of the population a known chance to be selected
multi stage sampling design
select random sample from high level of organization, from that group, randomly select a 2nd group...
margin of error
sets bound on size of likely error
undercoverage
occurs when some members of population can't be chosen in a sample
nonresponse
occurs when an individual chosen for a sample can't be contacted or refuses to participate
response bias
a systematic pattern of incorrect responses in a sample survey
wording of questions
the most important influence on answers given to a sample survey
observational study
observes individuals and measures variables of interest but does not attempt to influence the responses
experiment
deliberately imposes some treatment on individuals to measure their responses
confounding
occurs when 2 variables are associated in such a way that their effects on a response variable can't be distinguished from each other
treatment
a specific condition applied to individuals in an experiment
experimental units
the smallest collection of individuals to which treatments are applied
subjects
when the experimental units are human beings
factor
the explanatory variables in an experiment
level
treatments when studying the joint effects of several factors
completely randomized design
the treatments are assigned to all experimental units completely by chance
control group
group that receives an inactive treatment or an existing baseline treatment
placebo effect
the response to a dummy treatment
statistically significant
an observed effect so large it would rarely occur by chance
block
a group of experimental units or subjects that are similar in ways that are 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
infer about pop: yes
infer about cause and effect: yes
were individuals randomly assigned groups: yes
were individuals randomly selected: yes
infer about pop: no
infer about cause and effect: yes
were individuals randomly assigned groups: yes
were individuals randomly selected: no
infer about pop: yes
infer about cause and effect: no
were individuals randomly assigned groups: no
were individuals randomly selected: yes
infer about pop: no
infer about cause and effect: no
were individuals randomly assigned groups: no
were individuals randomly selected: no
Sets with similar terms