stats 355

based on haphazardly selected individual cases

data that were produced in the past for some other purpose but that may help answer a present question

observe individuals and measure variables of interest but do not attempt to influence the responses

deliberately impose some treatment on individuals and observe their responses

individuals on which the experiment is done

when the experimental units are human beings

a specific experimental condition applied to the units is called:

When the design of a study systematically favors certain outcomes

The group of patients who received a sham treatment

An observed effect so large that it would rarely occur by chance is called:

neither subjects themselves nor the medical personnel who worked with them knew which treament any subject had received

a group of experimental units or subjects that are known before the experiment to be similar in some way that is expected to affect the response to the treatments

the random assignment of units to treatments is carried out separately within each block

the basic principles of statistical design of experiments:

entire group of individuals that we want information about is called:

part of the population that we actually examine in order to gather information

consists of people who choose themselves by responding to a general appeal

size of n consists of n individuals from the population chosen in such a way that every set of n individuals has an equal chance to e the sample actually selected

a sample chosen by chance

divide the population into groups of similar individuals, then choose a seperate SRS in each stratum and combine these STSs to form the full sample

occurs when some groups in the population are left out of the process of choosing the sample

occurs when an individual chosen for the sample can't be contacted or does not cooperate

When their effects on a response variable connot be distinguished from each other

the observed associations between two variables are due to: