Unit 3 Review

the entire group of individuals we want information about

collects data from every individual in the population

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

if the value you want to know gets underestimated or overestimated

chooses the individuals easiest to reach; results in bias

sample consists of people who choose themselves by responding to a general invitation

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

where each entry is equally likely to be any of the 10 digits 0 through 9 and the entries of independent of each other

Label each individual in the population numerically and use the Table to select labels at random

classify the population into groups of similar individuals called strata, then choose a separate SRS in each stratum and combine to form the sample

classify the population of groups of individual located near each other, then choose and SRS of the clusters, and all the individuals in the chosen clusters are included in the sample

occurs when some members of the population cannot be chosen in a sample

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

a systematic pattern of incorrect responses in a sample survey

the most important influence on the answers given to s

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

imposes some treatment on individuals to measure their responses; cause and effect

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

a specific condition applied to the individual in an experiment

the smallest collection of individual to which treatments are applied

when the units are human beings

1. Comparison - design compares 2 or more treatments

2. Random assignment - assign experimental units to treatment to balance the effects of confounding variables

3. Control - keep other variables the same for all groups

4. Replication - use enough units that differences in the effects of the treatments can be distinguished from ones between the groups

an observed effect so large it would rarely occur by chance

treatments are assigned to all experimental units by chance

receives an inactive treatment or existing baseline treatment

response to dummy treatment

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

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 treatments

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

each block consists of a matching pair of similar experimental units