BNAD 276 - CH. 8,9,10

If 95% confidence interval for the mean value of a store's customer accounts is computed as $850 +/- 70, then the null hypothesis of a two-tailed hypothesis test would be rejected if the value of u0 is less than $_________ or greater than $_________

$780 and $920

We do NOT reject the null hypothesis when the p-value is

greater than or equal to alpha

We use ____ tests to address conflicts between two competing views on a particular population parameter

hypothesis

Two or more samples are considered independent if the process that generates one sample

is completely separate from the process that generates the other sample

a confidence interval for the mean difference follows the general format of a point estimate +/-

margin of error

when comparing two population means, their hypothesized difference

may assume any value

For matched-pairs sampling, the parameter of interest is referred to as the

mean difference

The estimator follows a normal distribution when the underlying population follows ______ distribution

normal

In order to derive a confidence interval for the population mean, the estimator must have a

normal sampling distribution

A two tailed test of the population mean is conducted at alpha = 0.10. The calculated test statistics is z=1.55 and p(z > 1.55) =0.0606. The null hypothesis should

not be rejected since the p-value = 0.1212 > 0.10

In hypothesis testing, two correct decisions are possible:

not rejecting the null hypothesis when it is true, rejecting the null hypothesis when the null hypothesis is false

when testing u, the p-value is the probability of obtaining a sample mean at least as large or at least as small as the one derived from a given sample, assuming the _________ hypothesis is true

null

A quality control officer believes that the average time of use for AAA batteries differs from the claimed 8.5 hours. The QC officer takes a random sample of 30 AAA batteries and finds that the sample mean is 8.7 hours. State the null and alternative hypothesis for testing the officer's claim.

null hypothesis u = 8.5, and alternative hypothesis does not equal 8.5

The hypothesis denoted by H0 is the ____ hypothesis and the hypothesis denoted by Ha is the ___ hypothesis

null, alternative

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

widens

What is the most typical form of a calculated confidence interval?

Point estimate + & - margin of error

a type I error is commonly denoted as

alpha

An important final conclusion to a statistical test is to ____

clearly interpret the results in terms of the initial claim

Matched-pairs sampling is an example of

dependent sampling

A type II error occurs when we

do not reject the null hypothesis when it is actually false

A 95% confidence interval for the population proportion is calculated as (0.40, 1.00) The margin of error for this interval is _____

0.30

For a 95% confidence interval in which the value of the standard deviation is known, there is a 95% probability that the sample mean will fall in the interval u +/- _____ x standard deviation/ square root of n

1.96

A certain type of light bulb is advertised to have a life of about 100 hours of use. With a certain level of confidence, it is advertised that the life is between 90 and 110 hours. If 100 hours it the point estimate, then the margin of error is

10 hours

The following table lists tdf values for selected upper-tail probabilities and degrees of freedom df. If df = 5 and alpha = 0.05, find t(a/2, df)

2.571

A sample of 25 is drawn from a normal population. A sample mean of 50 is calculated. For a 95% confidence interval, the margin of error is 10. A 95% confidence interval for the mean is

50 + & - 10

The alternative hypothesis for a two-sided test for a population mean would be denoted as

HA : u does not equal u0

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

p, pbar

The two equivalent methods to solve a hypothesis

p-value approach and the critical value approach

in a hypothesis test, u0 and p0 are hypothesized values of the ____ mean and the ____ proportion, respectively.

population, population

The critical value approach specifies a region of values, called the _______. if the test statistic falls into this region, we reject the _____.

rejection region, null hypothesis

The point estimate for the difference between two population means is represented by the difference between two

sample means

We calculate the __________ as a point estimate of an unknown population variance.

sample variance

The most practical way to reduce the margin of error is by

selecting a larger sample size

Put the following steps in the p-value approach to hypothesis testing in the correct order.

specify the null and alternative hypotheses, calculate the value of the rest statistic and its p-value, state the conclusion and interpret results

The two pieces of information that are necessary to determine the value of tdf are

the level of significance and the sample size or degrees of freedom

The basic principle of hypothesis testing is to assume that

the null hypothesis is true and see if the sample data contradicts this assumption

A confidence interval narrows if the following is accomplished:

the sample size increases and/or the chosen confidence level decreases