Exam 4 Intro Stats Reading Quizzes

TRUE OR FALSE: The confidence level is a measure of how well the method used to produce the confidence interval performs.

True

TRUE OR FALSE: The null hypothesis always gets the benefit of the doubt and is assumed to be true throughout the hypothesis-testing procedure.

True

TRUE OR FALSE: The null hypothesis, which we write as H0 is the conservative, status-quo, business-as-usual statement about a population parameter.

True

TRUE OR FALSE: The p-value is a probability. Assuming the null hypothesis is true, the p-value is the probability that if the experiment were repeated, you would get a test statistic as extreme as or more extreme than the one you actually got.

True

Which of the following value(s) for the significance level α are good choice(s)?

.05 or all of the above

The t-distributions are... symmetric unimodal "bell-shaped" All of the above

All of the above

Which of the following conditions are necessary for the distribution of the z-statistic to be a standard normal distribution? The sample is collected randomly The sample size, n, must be large enough: np>=10 and n(1-p)>=10. If without replacement, then population needs to be 10x larger than sample. Each observation must be independent. All of the above

All of the above

What is the formula for the z-test statistic? Z = (observed value - null value)/ SE Z = (p-hat - pnaught)/SE Both of these

Both of these

Which of the following are way(s) in which we can report a confidence interval? A. (lower boundary, upper boundary) B. Estimate plus or minus the margin of error C. Mean plus or minus the standard deviation D. Both A) and B) above E. Both A) and C) above

D. Both A) and B) above

If the p-value is greater than α then the appropriate conclusion is (check ALL that apply): Fail to reject Ho Accept Ho There is not sufficient evidence to support Ha All of the above

Fail to reject Ho There is not sufficient evidence to support Ha

TRUE OR FALSE: Hypotheses are always statements about sample statistics.

False

TRUE OR FALSE: It is correct to say that a particular confidence interval has a 95% (or any other percent) chance of including the true population parameter.

False

TRUE OR FALSE: The accuracy of an estimator is measured by the standard error.

False

TRUE OR FALSE: The precision of an estimator is measured by the bias.

False

TRUE OR FALSE: The standard error of the sample mean gets larger with a larger sample size.

False

True or False: Hypotheses are always statements about population statistics.

False

There are three basic pairs of hypotheses. A two-tailed test has which of the following hypotheses?

H0: p = p0 and Ha: p ≠ p0

There are three basic pairs of hypotheses. The one-tailed (left) one-sample t-test has the following hypotheses:

H0: µ = µ0 and Ha: µ < µ0

The confidence level measures

How often the estimation method is successful

A confidence interval is often reported as an estimate plus or minus some amount. This "some amount" is called

Margin of error

To obtain a 95% confidence level for capturing the population mean, we use a margin of error of 1.96 standard errors 2.58 standard errors 1.96 standard errors 1.645 standard errors 1.28 standard errors None of these

None of these

To achieve a significance level of α, if the p-value is less than (or equal to) α, then

Reject the null hypothesis

The probability of rejecting the null hypothesis when, in fact, the null hypothesis is true is called the

Significance Level

Two different studies each did the coin spinning experiment with a two tailed alternative. In Study 1, z = -2.25. In Study 2, z = 1.98. Which of these statistics has the smaller p-value?

Study 1

TRUE OR FALSE: A confidence interval provides a range of plausible values for a population parameter.

True

TRUE OR FALSE: A sampling distribution is a probability distribution of a statistic.

True

TRUE OR FALSE: A small p-value suggests that a surprising outcome has occurred and discredits the null hypothesis.

True

TRUE OR FALSE: During hypothesis testing, if we decide at the last step that the observed outcome is extremely unusual under this assumption, then and only then do we reject the null hypothesis.

True

TRUE OR FALSE: For all populations, the sample mean of a randomly selected sample is an unbiased estimator of the population mean.

True

TRUE OR FALSE: If the Central Limit Theorem conditions fail to be met for a hypothesis test, the z-statistic will not follow a standard normal distribution when the null hypothesis is true.

True

TRUE OR FALSE: If the null hypothesis is true, then the z-statistic will be close to 0. Therefore, the farther the z-statistic is from 0, the more the null hypothesis is discredited.

True

TRUE OR FALSE: In our textbook, the null hypothesis always has an equal sign, no matter which alternative hypothesis is used.

True

TRUE OR FALSE: It is correct to say that the process that produces intervals captures the true population parameter 95% of the time.

True

TRUE OR FALSE: The alternative hypothesis, Ha, is the research hypothesis. It is usually a statement about the value of a parameter that we hope to demonstrate is true.

True

TRUE OR FALSE: The p-value is a probability. Assuming the null hypothesis is true, the p-value is the probability that if the experiment were repeated, you would get a test statistic as extreme as or more extreme than the one you actually obtained.

True

TRUE OR FALSE: The standard deviation of the sampling distribution is what we call the standard error.

True

TRUE OR FALSE: When a statistic of the sampling distribution is the same value as the population parameter, we say that the statistic is an unbiased estimator.

True

True or False: Confidence intervals are a technique for communicating an estimate of the mean along with a measure of our uncertainty in that estimate.

True

True or False: In hypothesis testing, values of the t-statistic that are far from 0 tend to discredit the null hypothesis.

True

True or False: The p-value tells us the probability that we would get a t-statistic as extreme as or more extreme than what we observed.

True

The sample mean is... the arithmetic average of a sample of data an estimate of the population mean unbiased, if the sample is a random sample all of the above

all of the above

The t-distribution's shape depends on only one parameter, called the

degrees of freedom

What is the statistic that compares the observed proportion to the expected proportion?

the one-proportion z-test statistic