BSTATS Ch.8

The required sample size for estimating a population proportion is largest when p̂ equals

0.50

A 95% confidence interval for the population mean is constructed as 6 ± 2. What is the confidence coefficient?

0.95

The confidence coefficient equal to

1-a

The confidence coefficient equals

1-a

For a 95% confidence interval for the population mean, if samples of size n are drawn repeatedly from a given population, then

5% of the sample means will fall outside of the corresponding confidence interval

Which of the following are components of the formula for selecting n to estimate p?

<p Z a/2 E

Which of the following characteristics describe both the z and tdf distributions?

Bell shaped, asymptotic tails, symmetric around 0

Suppose you are constructing a confidence interval for the population mean. For a given confidence level and sample size, the width of the interval is wider for a

Larger standard deviation

A confidence interval is constructed by using the point estimate as a base, to which we add and subtract the _____

Margin of error

A confidence interval narrows if the following is accomplished:

The sample size increases and the chosen confidence level decreases

How do the tdf and z distributions differ?

The tdf distribution has broader tails (it is flatter around zero)

The Greek letter ______ denotes the level of significance.

a

The allowed probability that an interval estimate of a population mean will not contain μ is referred to as the

level of significance

The parameter ______ represents the proportion of successes in a population and the statistic ______ represents the proportion of successes in a sample.

p, /p

When rounding a noninteger sample size, you always round

up

For a given confidence level and sample size, the larger the population standard deviation, the_______ the confidence interval.

wider or larger

When calculating the required sample size for a proportion CI, if you do not have an estimate of the proportion, you should use a value of

0.50

For the 90% confidence interval, the confidence coefficient equals ____and α equals_____

0.90 and 0.10

Whenever we construct a confidence interval for the population mean, the margin of error includes the standard error of .X and the

Desired level of confidence

When the confidence level increases from 95% to 99%, the confidence interval for the population mean _______

Widens

As df increases, the tdf distribution becomes similar to the _________distribution

Z

Which of the following is the correct formula for the margin of error in the interval estimation of p?

Z a/2 /p(1-/p) divide n sqrt.

The sampling distribution of the sample proportion can be approximated by a normal distribution when _____

np>- 5 and n(1-p) >- 5

Which of the following are components of the formula for selecting n to estimate μ?

o and p < z a/2

The ______ /p is used as the point estimator for the ______ p

Sample proportion, population proportion

If repeated samples of size n are taken from a normal population with an unknown variance, then the statistic T=______ follows the t distribution with n - 1 degrees of freedom

/X-U divide S/sqrt.n

Larger sample sizes _____ more.

Cost

For a 95% confidence interval, α =

0.05

A t distribution

Has slightly broader tails than the Z distribution

Suppose you are constructing a confidence interval for the population mean. For a given sample size and standard deviation, the width of the interval is wider for a

Higher confidence level

One way to reduce the margin of error is to

Increase the sample size

A confidence interval is also referred to as an

Interval estimate

The parameter p represents the _______

Population proportion

Suppose you are constructing a confidence interval for the population mean. For a given confidence level and standard deviation, the width of the interval is wider for a

Smaller sample size

True or false: the tdf distribution has slightly broader tails than the z distribution.

True

In a confidence interval, the _____ accounts for the standard error of the estimator and the desired confidence level of the interval.

Margin of error

In order to construct a confidence interval for the population mean μ or the population proportion p, it is essential that the sampling distributions of /X and /P follow, or approximately follow, a ______ distribution

Normal

The formula for a mean confidence interval is valid only if /X (approximately) follows a ____ distribution.

Normal

When the sample size is sufficiently large, we can approximate the sampling distribution of the sample proportion using the __________ distribution

Normal

In order to derive a confidence interval for μ, the estimator /X must have a

Normal sampling distribution

The two main components of a confidence interval are the

Point estimate and margin of error

When estimating the population mean, the tdf distribution is used when the ________is unknown.

Population variance

/X= Za/2= n= o= o/sqrt. n=

-Sample mean -Value from the standard normal table -Sample size -Standard deviation -Standard error

You use sample statistics to make inferences about the unknown population ______

Parameters

When a statistic is used to estimate a parameter, it is referred to as an

estimator

The probability of error α for a 99% confidence interval is

0.01

The confidence level is equal to ______

100 x (1-a)%

When examining the possible outcome of an election, what type of confidence interval is most suitable for estimating the current support for a candidate?

Confidence interval for the population proportion

The variability between samples is measured by the ________ of /X

Standard Error

True or false: A confidence interval provides a range of values that should contain a population parameter with a certain level of confidence.

True

True or false: For a given sample size n and population standard deviation σ, the lower the confidence level 100(1-α)%, the narrower the confidence interval

True

The sampling distribution of estimator /X follows a normal distribution when the underlying population is normally distributed and/or when the sample size is large enough. As a "rule of thumb" we use a sample size of at least

30 or thirty

Suppose you are constructing a confidence interval for the population mean. For a given sample size and population standard deviation, how will the width of the interval change as the confidence level increases?

It gets larger