new quiz 7 Flashcards
the way a sample is selected is called the ___________or ____________
SAMPLING PLAN, EXPERIMENTAL DESIGN
a commonly used sampling plan in which every sample of size n has the same chance of being selected.
Simple Random Sampling
A simple random sample can also be called a _____
random sample
when the data already exists and you are just picking the random data for sample
observational study
Most sample_____, in which info is gathered in a questionnaire, fall into this category, obervational study
surveys
when population consists of 2 or more subpopulations, called ______, a sampling plan that ensures that each subpopulations is represented in the sample is called a ________ random sample
strata, stratified
Stratified random sampling involves selecting a simple random sample from each of a given # of subpops. or strata
true
A cluster sample is a simple random sample of clusters from the available _____ in the populations
clusters
Sometimes the population to be sampled is _____ such as an alphabetical list of people with driver’s license, then we can use a _________ random sample
ordered, systematic
A ________ systematic randon sample involves the random selection of one of the first K elements in an ordered population and then the systematic selection of every Kth element after that
1 of K
a sample that can be easily and simply obtained without random selection
convenience sample
a convenience sample is non-random and can not be used for making inferences
true
when you select a random sample, the numerical descriptive measure you calculated from the sample are called…
statistics`
These statistics vary or change from sample to sample, that is they are _______
random variables
The probability distribution for statistics are called _______ distributions
sampling
One important statistical theorem that describes the sampling distribution of statistics that are sums of averages is…
central limit theorem
Under rather general conditions, this theorem states that sums and means of random samples of measurements drawn from a population tend to have an approximately______ distribution
normal
The spread of the distribution is slowly decreasing as the sample size n increases (true or false)
trueeeee
CLT- if random samples of n observations are drawn from a non-normal population with finite mean and standard deviation, then , when n is large, the sample mean follows a normal distribution with mean ____ and standard deviation
ϻ, σ/√(n)
The CLT can be restated to apply to the sum of the sample measurements which as n becomes large, also has an approximate _______ distribution with mean _________ and standard deviation ______
normal, n x ϻ, √(n) x σ
the standard deviation of a statistic used as an estimator of a population parameter is also called _______ of the estimator (SE), because it refers to the _______ of the estimator
standard error, error
SE( sample mean)=
σ/√(n)
estimating or predicting the value of the parameter
estimation
making a decision about the value of a parameter based on a preconceived idea about what the value might be
hypothesis test
an ______ is a rule usually expressed as a formula that tells us how to calculate an estimate based on info in a sample
estimator
a single # is calculated to estimate population parameter
point estimator
2 numbers are calculated to form an interval within which the parameter is expected to lie withing
interval estimator
a point estimator is said to be ____ if the mean of its distribution is the true value of the parameter being estimated, otherwise, the estimator is said to be ____
unbiased, biased
the _____ ( as measured by the variance) of the estimator’s sampling distribution should be as small as possible
spread ( better if spread is more concentrated around true value)
The distance between an estimate and the true value of the parameter is called the ______ of estimation
error
the probability that the true value falls into interval is called the ________. (1- α) x 100%
confidence
If the sample size is large enough, then CLT applies so we can work with ________ distributions
normal
1-α is the probability that the interval covers the true value. The smaller the α is, the _____ interval is
wider
if n increases, the interval is getting _____. This is because large n means more information, therefore less uncertainty
narrower
