ISDS Test 3
If a equals 0.01, then the confidence coefficient equals ____.
0.99
The confidence level is equal to 100 x (_____) %.
1-a
What is the value of z-a/2 for a 90% confidence interval for the population mean?
1.645
For a 95% confidence interval for the population mean, if samples of size n are drawn repeatedly from a given population, then ____% of the sample means will fall {outside of/within} the corresponding confidence interval.
5; outside of
The parameter p represents the...
population proportion
Performing a one-way ANOVA test, instead of performing a series of two-sample t tests, _____ the risk of incorrectly rejecting the null hypothesis.
reduces
The confidence level affects the margin of error but not the ______ error.
standard
True or false: We use ANOVA to test for differences between population means by examining the amount of variability between the samples relative to the amount of variability within the samples.
true
Between-treatment variability is based on a weighted sum of squared differences between the sample means and the
grand mean
A completely randomized sample design draws from ____ samples.
independent random
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 one-way ANOVA test is better than using a series of two-sample t tests because conducting a series of two-sample t tests inflates the risk of committing...
a Type I error
In order to determine if there is a difference between the means of 3 or more populations, we use...
analysis of variance (ANOVA)
The standard error of the sample mean is NOT affected by the
confidence level
An estimator that tends to produce more accurate estimates of the population parameter as the sample size increases is BEST characterized as a(n) ______ estimator.
consistent
True or False: ANOVA is a statistical technique used to determine if there is a difference in three or more population standard deviations.
false
We calculate a ____ estimate of the common variance, denoted sp2, when two populations are assumed to have the same variance.
pooled
The sample proportion is a point estimator of the...
population proportion (p)
When constructing a confidence interval for the population mean, the factors that affect the width of the confidence interval for a *given* standard deviation are...
the confidence level and the sample size
When constructing a confidence interval for the population mean when the population standard deviation is unknown, the degrees of freedom for the t distribution are defined as...
n-1
In one-way ANOVA, the error sum of squares (SSE) is the sum of
the weighted sample variances of each treatment
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 is the point estimate, the margin of error is _____.
10 hours
What is the confidence level if a = 0.10?
90%
The test statistic for a one-way ANOVA test follows the
F df1, df2 distribution
When comparing two population means, their hypothesized difference must...
assume any value
In one-way ANOVA, two independent estimates of the common population variance, o2 are estimated. These estimates are commonly referred to as
between-treatments variability and within-treatments variability
Suppose you want to perform a test to compare the mean GPA of all freshman with the mean GPA of all sophomores in a college. What type of sampling is required for this test?
independent sampling with quantitative data
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
The allowed probability that an interval estimate of a population mean will not contain μ is referred to as the...
level of significance
A confidence interval is constructed by using the point estimate as a base, to which we add and subtract the...
margin of error
An ANOVA test determines if differences exist between the _____ of three or more populations.
mean
In order to construct a confidence interval for μ, the sampling distribution of the estimator x̅ must follow or approximately follow a(n) ____ distribution.
normal
The estimator x̅ follows a normal distribution when the underlying population follows a _____ distribution.
normal
When the sample size is sufficiently large, we can approximate the sampling distribution of the sample proportion using the...
normal distributuion
The sample statistic p-bar is an estimator of ____.
p
What is the most typical form of a calculated confidence interval?
point estimate +/- (±) margin of error
The sample mean is a point estimator of the...
population mean (μ)
When examining the possible outcome of an election, what type of confidence interval is most suitable for estimating the current support for a candidate?
population proportion
When estimating the population mean, the t-dt distribution is used when the...
population variance is unknown
Which of the following is a descriptive measure for qualitative variable?
proportion
In a one-way ANOVA test, if the amount of variability between treatments is significantly greater than the amount of variability within treatments, then we...
reject the null hypothesis of equal population means
The one-way ANOVA test is always a _____ test.
right-tailed
When the population standard deviation is unknown, the standard error for the sample mean is calculated as...
s/√n
We calculate the ____ as a point estimate of an unknown population variance.
sample variance
A 95% confidence interval for the difference between two population means is -1.5 ± 0.5, indicating that at the 5% significance level, the resulting difference is...
significant and the population means differ
An estimator is unbiased if the average value of the estimator is equal to...
the parameter being estimated
Which of the following is NOT an assumption for performing a one-way ANOVA? the population correlation coefficients indicate a strong linear relationship, the populations are normally distributed, the samples are selected independently, the population standard deviations are unknown but assumed equal
the population correlation coefficients indicate a strong linear relationship
A confidence interval narrows if the following is accomplished: the sample size decreases, the chosen confidence level increases, the sample size increases, the chosen confidence level decreases
the sample size increases, the chosen confidence level decreases
The two pieces of information that are necessary to determine the value of t-df are...
the sample size or degrees of freedom (n) and the level of significance
In one-way ANOVA, the sum of squares due to treatments (SSTR) is the sum of
the weighted squared differences between the samples mean and the grand mean
Since ANOVA techniques were originally developed in connection with agricultural experiments, the term ____ is often used to identify the populations being examined for an ANOVA analysis.
treatment
True or False: One-way ANOVA analysis does not require that all means differ from one another.
true
True or False: the t-df distribution has slightly broader tails than the z distribution.
true
True or false: The calculation of the test statistic when testing the difference between two population means is valid when (1) the underlying distributions of the two populations are normal or (2) both sample sizes are sufficiently large.
true
True or false: The formula for a confidence interval for the difference in population means when population variances are unknown but assumed equal, can incorporate a pooled estimate of common variance.
true
True or false: the t-df distribution is bell-shaped and symmetric around 0.
true
true or false: a point estimator is a function of a random sample used to make inferences about the value of an unknown population parameter
true
Some of the desirable properties of a point estimator include...
unbiasedness, consistency, and efficiency
In one-way ANOVA within-treatments variability is based on the
variablity within each sample
In most applications, the hypothesized difference between two population means is ____.
zero
The sample statistic x-bar is an estimator of ____.
μ
x̅ and p-bar are the unbiased estimators of
μ and p
