ISDS 2000 ch 7

estimate

a particular value if an estimator

random samples of the size 100 are taken from a population whose population proportion is 0.40. the expected value of the sample proportion is ___

0.40

a population has a mean of 100 and a standard deviation of 10. a random sample of 25 is selected. the expected value of X is equal to ____

100

a population consists of all items of interest in a statistical problem, whereas a ___ is a subset of the population

sample

a ___ is a random variable whose value depends on the chosen random sample

statistic

We use a calculated sample _____ to make inferences about an unknown population _____.

statistic, parameter

in ___, the population is divided up into strata and then randomly selected observations are taken proportionally from each stratum

stratified random sampling

the standard deviation of X is calculated as

the positive square root of variance X

true or false: if we had access to data that included the entire population, then the values of the parameters would be known and n statistical inference would be required

true

the central limit theorem states that, for any distribution, as n gets larger the sampling distribution of the same mean becomes

closer to a normal distribution

when a sample statistic is used to make inferences about a population parameter, it is referred to as an

estimator

the sample size required to approximate the normal distribution depends on

how much the population varies from normality

stratified sampling is referred to cluster sampling when objective is

increase precision

a sample statistic is considered biased if

it systemically over or under estimates the unknown parameter being estimated

the further a population proportion deviates from p=0.50, the ___ the sample size required in order to satisfy a normal approximation

larger

statistic

random variable

parameter

constant

what is a primary requirement of a "good" sample?

it is representative of the population we are trying to describe

as a general guideline, the normal distribution approximation can be used to describe the sampling distribution of the sample mean when

n>30

the probability distribution of the sample mean is commonly referred to as the ___

sampling distribution of X

nonresponse bias occurs when

Those responding to a survey or poll differ systematically from the non-respondents