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