Stats Vocab Chapters 10, 11, and 12

biased

biased

any systematic failure of a sampling method to represent its population

strata

when groups of experimental units are similar, they are gathered into these groups

census

a sample that consists of the entire population

cluster

sampling design in which entire groups are chosen at random

completely randomized

type of experiment in which all experimental units have an equal chance of receiving any treatment

confounding

when the levels of one factor are associated with the levels of another factor so their effects cannot be separated

control

aspects of the experiment that we know may have an effect on the response, but that are not the factors being studied

control group

experimental units assigned to a baseline treatment level

convenience

sampling design where individuals are chosen based on who is easily available

double blind

neither the subjects nor the people who have contact with them know which treatment a subject has received

experimental units

individuals on which an experiment is done

experiments

study in which subjects are randomly assigned to treatments

factor

variable whose levels are controlled by the experimenter

heterogeneous

not similar in makeup

homogeneous

similar in makeup

level

specific values that the experimenter chooses a factor

matched pairs

type of study in which subjects who are similar in ways not under study may be grouped together and then compared with each other on the variables of interest

multistage

sampling schemes that combine several sampling methods

nonresponse

type of bias that is problematic because the intended sample is incomplete

observational study

study based on data in which no treatments have been assigned to subjects

outcome

an individual result of a component of a simulation

placebo

treatment known to have no effect, administered so that all groups experience the same conditions

placebo effect

the tendency of many human subjects to show a response even when administered a fake treatment

population

the entire group of individuals or instances about whom we hope to learn

prospective

observational study in which subjects are followed to observe future outcomes

random behavior

an occurrence for which we know what outcomes could happen, but not which particular values will happen

randomization

process by which each individual is given a fair chance of selection

response

type of bias that is problematic because false information may be given

retrospective

observational study in which subjects are selected and then their previous conditions or behaviors are determined

sample

a (representative) subset of a population, examined in hope of learning about a population

simple random

sampling design in which each set of n elements in the population has an equal chance of selection

sampling frame

a list of individuals from whom the sample is drawn

sampling variability

the natural tendency of randomly drawn samples to differ, one from another

sample survey

a study that asks questions of a sample drawn from some population in the hope of learning something about the entire population

simulation

models random events by using random numbers to specify outcomes with relative frequencies that correspond to the true real-world relative frequencies we are trying to model

single blind

when either the subjects or the people who have contact with them do not know which treatment a subject has received

statistically significant

when an observed difference is too large to believe that it is likely to have occurred naturally

block

a subdivision of the population

stratified

sampling design in which the population is divided into several strata, and random samples are then drawn from each stratum

subjects

people who are studied

systematic

sample drawn by select an individual from a list and then each of the next N individuals from the sampling frame

treatment

the process or intervention applied to randomly assigned experimental units

trial

the sequence of several components representing events that we are pretending will take place

undercoverage

type of bias that is problematic because some groups are not represented in the sample

voluntary response

type of bias that is problematic because those who volunteer tend to have strong negative opinions

voluntary response

sampling design where individuals can choose on their own whether to participate in the sample

wording bias

a type of response bias where the question is posed to achieve a desired result