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18 terms

Vocab #8

STUDY
PLAY
stratified random sample
groups of interest (strata) chosen in such a way that they appear in approximately the same proportions in the sample as in the population
subjects
human experimental units
survey
obtaining responses to questions from individuals
symmetric
data values distributed equally above and below the center of the distribution
systematic bias
the mean of the sampling distribution of a statistic does not equal the mean of the population; see unbiased estimate
systematic sample
probability sample in which one of the first n subjects is chosen at random for the sample and then each nth person after that is chosen for the sample
t distribution
the distribution with n-1 degrees of freedom for the t statistic
t statistic
t=xbar-mu/x/√n
third quartile
75th percentile
treatment variable
explains changes in response variable; treatment variable; independent variable
tree diagram
graphical technique for showing all possible outcomes in a probability experiment
two-sided alternative
alternative hypothesis that can vary from the null in either direction; values much greater than or much less than the null provide evidence against the null
two-sided test
a hypothesis test with a two-sided alternative
two-way table
table that lists the outcomes of two categorical variables; the values of one category are given as the row variable, and the values of the other category are given as the column variable; also called a contingency table
type-I error
the error made when a true hypothesis is rejected
type-II error
the error made when a false hypothesis is not rejected
unbiased estimate
mean of the sampling distribution for the estimate equals the parameter being estimate
undercoverage
some groups in a population are not included in a sample from that population