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Statistics 2.1-2.4

Terms in this set (27)

Placebo
a treatment that has the appearance of the treatment of interest but contains no active ingredients
Census
obtaining information for a whole population
Selection Bias
tendency for samples to differ from the corresponding population as a result of systematic exclusion of some part of the population
Measurement or Response Bias
tendency for samples to differ from the corresponding population because the method of observation tends to produce values that differ from the true value
Nonresponse Bias
tendency for samples to differ from the corresponding population because data are not obtained from all individuals selected for inclusion in the sample
Simple Random Sample of Size N
sample that is selected from a population in a way that ensures that every different possible sample of the desired size has the same chance of being selected
Sampling Frame
list of the objects or individuals in the population
Sampling with Replacement
after an individual from the population is selected for inclusion in the sample and the corresponding data are recorded, the individual is placed back in the popoulation and can be selected again in the sampling process
Sampling without replacement
once an individual from the population is selected, it may not be selected again in the sampling process
Stratified Sampling
the entire population can be divdied into a set of non-overlapping subgroups
Strata
subgroups
Cluster Sampling
dividing the population of interest into non-overlapping groups called clusters
Convenience sample
using an easily available or convenient group to form a sample
Observational Study
the investigator observes characteristics of a subset of the members of one or more existing populations
Factors
variables that a researcher manipulates to create the experimental conditions
experiment
investigator observes how a response variable behaves when the researcher manipulates one or more factors
confounding variables
one that is related to both group membership and the response variable of interest in research of study
experimental condition or treatment
any particular combination of values for the explanatory variables
design
overall plan for conducting an experiment
extraneous factor
one that is not of interest in the current study but is thought to affect the response variable
blocking
creates groups that are similar with respect to blocking factors; then all treatments are tried in each block
confounded
effects on the response variable cannot be distinguished from one another
randomization
proceses that handles extraneous factors by the use of random assignment to experimental groups
replication
ensuring that there is an adequate number of observations for each experimental condition
treatment
a specific experimental condition applied to the units
explanatory variable
two treatments together are the possible values
response variable
what you measure
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