AP Statistics Unit 3 Vocab

the entire group of individuals we want information about

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

collects data from every individual in the population

a group of individuals in a population that are located near each other

occurs when two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other

means keeping other variables constant for all experimental units

used to provide a baseline for comparing the effects of other treatments

choosing individuals from the population who are easy to reach

experiment where neither the subjects nor those who interact with them and measure the response variable know which treatment a subject received

deliberately imposes some treatment on individuals to measure their responses

may help explain or predict changes in a response variable

variable that is manipulated and may cause a change in the response variable

occurs when an individual chosen for the sample can’t be contacted or refuses to participate

observes individuals and measures variables of interest but does not attempt to influence the responses

a treatment that has no active ingredient, but is otherwise like other treatments

describes the fact that some subjects in an experiment will respond favorably to any treatment, even an inactive treatment

experimental units are assigned to treatments using a chance process

using enough experimental units to distinguish a difference in the effects of the treatments from chance variation due to the random assignment

occurs when there is a systematic pattern of inaccurate answers to a survey question

measures the outcome of a study

a subset of individuals in the population from which we actually collect data

a study that collects data from a sample that is chosen to represent a specific population

refers to the fact that different random samples of the same size from the same population produce different estimates

a sample of size n is chosen in such a way that every group of n individuals in the population has an equal chance to be selected as the sample

experiment where either the subjects don’t know which treatment they are receiving or the people who interact with them and measure the response variable don’t know which subjects are receiving which treatment

when the observed results of a study are too unusual to be explained by chance alone; occurs less than 5% of the time

groups of individuals in a population who share characteristics thought to be associated with the variables being measured in a study

selects a sample from an ordered arrangement of the population by randomly selecting one of the first k individuals and choosing every kth individual thereafter

occurs when some members of the population are less likely to be chosen or cannot be chosen in a sample

allows people to choose to be in the sample by responding to a general invitation