Stats Exam 2 Ch 6-8
Unimodel and symmetric
A normal distribution is
Inferential statistics
Branch of statistics that uses sample statistics to estimate a population parameter or test a hypothesis about such a parameter is best referred to as
1-P (Z ≤ z)
How do we calculate P(Z>z)
Bias
If a sample statistic consistently over or under estimates a population parameter then it is
True
If we have access that included the entire population, then the values of the parameters would be known and no statistical inference would be required
False, it assumes a countable number of values
T/F A discrete random variable can assume an uncountable number of values
Continuous random variable
characterized by uncountable values bc it can take on any value within an interval or collection of intervals
Probability Density Function
counterpart to the probability mass function
sampling distribution of x̄
The probability distribution of the sample mean is referred to as
selection bias
this bias occurs when there is a systematic exclusion of certain groups from consideration for the sample
reduce the sampling variation of x̄ and p bar
we use the finite population correction factor to
estimator
when a sample statistic is used to make inferences about a population parameter, it is referred to as an
(σ / √n) √(N−n)/N-1)
when the finite population correction factor is applied to the sample mean, the resulting standard error for the sample mean is equal to
√(p(1-p)/n) times √((N-n)/(N-1))
when the finite population correction factor is applied to the sample proportion, the resulting standard error for the sample proportion is equal to
x = μ + zσ
in a normal distribution, in order to transform a standard normal value z into its unstandardized value x, we use what formula
z = x-μ / σ
in a normal distribution, in order to transform a value x into it standardized value z, we use which formula
It is representative of the population we are trying to describe
what is a primary requirement for a good sample
95%
For data normally distributed, ___% of the date will fall within 2 standard deviations of the mean
95%
For data normally distributed, the % of the data that falls within 2 standard deviations of the mean is
sample
population consists of all items of interest in a statistical probe, whereas a ______ is a subset of the population
√(p(1-p)/n)
standard deviation of p bar equals
to increase precision
stratified sampling is preferred to cluster sampling when the objective is
Proportion of successes in the population
the expected value of p bar is the
μ
the expected value of x̄ is equal to
0 and 1
the mean and variance of the standard normal distribution are
n ≥ 30
the normal distribution approximation can be used to describe the sampling distribution of the sample mean when
mean and variance
the normal distribution is completely described by these 2 parameters
by a discrete random variable
the number of defective light bulbs in a sample of 5 is represented by what type of variable
central limit theorem
theorem that allows us to use the normal probability distribution to approximate the sampling distribution of the sample mean whenever the sample size is large is known as the
0.5
Due to symmetry, the probability that the standard norma random variable Z is less than 0 is equal to
Continuous random variable
The temperature in Tampa, Florida during the month of July is an example of what type of variable
zero
the probability that a continuous random variable X assumes a particular value x is
Stratified random rampling
Kind of sampling that is most likely to be used by political pollsters who want to ensure that each religious group is represented in a sample
n ≥ 0.05N
we can use the finite population correction factor when
all items of interest
in a statistical problem, a population consists of
the probability that Z is less than or equal to a given z value
what does cumulative probabilities mean
stratified random sampling
in ______ sampling, the population is divided up into strata and then randomly selected observations are taken proportionately from each stratum
constant for all x between a and b, and otherwise 0
A continuous random variable has the uniform distribution on the interval [a,b] if its probability density function f(x) is
those responding to a survey or poll differ systematically from the non-respondents
Nonbias occurs when
Cluster sampling
_____ smapling involves dividing a population into mutually exclusive and exhaustive groups called clusters, and then selecting a random sample from these clusters for analysis
a bell shaped curve
a normal random variable is depicted with what
estimate
a particular value of an estimator is called an
subtracting the mean and then dividing by the standard deviation
a random variable x is transformed into z by
continuous uniform distribution
a random variable x with an equally likely chance of assuming any value within a specified range is said to have which distribution
.50
area under a normal curve below its expected value is
less than or equal to any value x
for a continuous random variable X, the cumulative distribution function F(x) provides the probability that X is
equal to one
for an continuous random variable, one characteristic of its probability density function is that the area under f(x) over all values of x is
5
general rule for using the finite correction factor is that the sample constitutes at least _____ percent of the population
the mean, median and mode are all equal
if X is a normally distributed random variable, then
compute x values for given probabilities
inverse transformations, x = μ + zσ is used to
less than one
the value of the finite correction factor is always
the sample is not representative of the population we are trying to describe
Whats a characteristic of a bad sample
x̄ = 20
_____ Is considered an estimate
