Chapter 8 Stat Quiz

A complete, testable hypothesis includes several defining elements, including which of the following? (Select all that apply)

- It explicitly identifies the groups being compared - It specifies the scale of measurement to be used - It states the direction of the effect or the nature of the expected difference in terms of the dependent variable

Arrange the hypothesis testing steps in their correct order.

- State the null and alternative hypotheses - Determine the alpha level - Determine the appropriate statistical test - Identify the critical values of the test statistic - Calculate the test statistic - Decide to reject H0 - Intepret the decision in terms of the original claim

Sort the following alpha levels from smallest to largest rejection region.

.01, .05, .08

With alpha set to .05 the probability of rejecting the null hypothesis when it is true is

.05

A graduate student has determined that for her research, β = .75. What is the power of her experiment?

.25

With alpha set to .05 the probability of failing to reject the null hypothesis when it is true is

.95

The statement, H1: µ ≠ k, would require a ___ -tailed test.

2

Your professor's study of the relationship between income and support for gun control led her to accept the null hypothesis that there is no relationship between these variables, even though there is. In this case, she has made a Type ______ error.

2

t test for less than

30

z test for greater than

30

Which of the following are key components of an experiment? (Select all that apply)

A null hypothesis and an alternative hypothesis, A statement defining how the results are to be measured and interpreted, Identification of the population of interest, Descriptions of the variables being tested

Sort these items into the correct order according to the scientific method.

Ask a question Do background research Construct a hypothesis Test the hypothesis Analyze the data and draw conclusions Communicate the results

the prob of a type II error increases as the type I error

DECREASES

Given a research hypothesis that the average test score of students in online class sections will be different from the average test score of students in classroom-based sections, identify the correct null hypothesis:

H0: µ1 = µ2

Given the statement, H1: µ1 > µ2, what is the correct null hypothesis?

H0: µ1 ≤ µ2

A result that is statistically significant does not mean that it is _________.

Important in the real world

What is the difference between an experimental and non-experimental study?

In an experimental study the IV is actively manipulated while in a non-experimental study the IV is not actively manipulated.

What is the function of the comparison distribution?

It provides the statistical distribution to which the results of a study are to be compared.

When alpha increases, both __________ and ______________ increase.

Power; probability of a Type I error

With a two-tailed test, the rejection region is __________.

Split between the two tails of the distribution

Alpha refers to __________.

The probability of making a Type I error

Which of the following defines a Type I error?

The probability of rejecting the null hypothesis when it is true

The population standard error of the mean (σ) is necessary for conducting ___________

The single-sample z test for means

Which of the following determines alpha?

The size of the rejection region

null rejected true

Type 1 error, probability alpha

null hypothesis

a statement about a population parameter that is assumed to be true unless there is convincing evidence to the contrary

The alternative hypothesis

a statement that is directly contradictory to the null hypothesis, summarizes the expected or predicted outcome of the investigation

hypothesis testing

a statistical procedure for testing whether a research hypothesis provides a plausible explanation for experimental findings

significance level of a hypothesis test is represented by

alpha

the probability of making a type I error=

alpha

if the null hypotheses can be rejected than the

alternative hypotheses can be supported

sample statistics are used to

assess the probability that the hypothesis in fact represents the true state of affairs

A researcher is planning a study and is considering various options for alpha. Selecting a larger alpha value will result in decreased _______

beta

Prob a of type II error is

beta (B)

The null and alternative hypotheses must be ________.

complementary

The null hypothesis is stated so as to be _________ to the alternative hypothesis.

complementary

null not rejected true

correct decision probability= 1- alpha

null rejected false

correct decision, probability= 1-B= power

what does alpha recognize?

corresponds to the size of the rejection region

Which of the following is the formula for degrees of freedom?

df=n-1

null hypothesis describes a null

difference in the outcome (no effect of the treatment)

If p is greater than alpha...

fail to reject Ho

Type II error

failing to reject the null when it is false

The appropriate comparison distribution for comparing an individual score to a known population parameter is a distribution of sample means.

false

The purpose of hypothesis testing is to establish the truth of the research hypothesis.

false

the larger the n the

greater the power of the test

the higher the value of alpha the

higher the p

critical first step in the scientific method

identification of the competing hypotheses (null and alternative)

write a hypothesis statement

identify the populations, iv and dv, the effect

Other things being equal, which of the following will increase the power of a hypothesis test?

increasing the sample size

The shape of the t-distribution

is similar to the normal curve, changes with sample size

P-value

is the calculated probability of obtaining a result at least as extreme as the one observed if the null hypothesis is true

contains "less than"

left tailed

A research hypothesis that makes a prediction of a lower score on a measure of the DV would require a ________.

left-tailed test

The appropriate comparison distribution to use when comparing a sample mean to a known population mean is a distribution of ______.

means

A two-tailed test is appropriate for a hypothesis that does not predict a outcome.

more than or less than

A researcher wants to determine whether Hispanic and Native American men have similar startle responses when presented with an unexpected stimulus event.

no

Comparison of high school males and females on amount of marijuana smoked during summer vacation.

no

null hypothesis is sometimes referred to as

no difference hypothesis

The null hypothesis is considered as the ______ outcome.

no effect

Most real-world research hypotheses are _________ in nature.

non directional

In hypothesis testing, which of the following is a statement about the population parameter that is assumed to be true by default?

null hypothesis

Statistical power refers to the probability of successfully rejecting the

null hypothesis

Along with whether a result has statistical significance, a researcher should also be concerned with whether the result has ____________ significance.

practical

The core logic of hypothesis testing is built around the concept of _______.

proof by contradiction

Sociologists want to test whether the number of homeless people in a particular urban area is increasing. In 2010, the average number of homeless people per day who sought shelter was 42.3 (σ = 6.2). Data from the current year reveal that the mean number of people seeking shelter per day is 45.3. What is the correct statistical decision?

reject

if p is smaller than alpha

reject

type I error

rejecting the null hypothesis when it is true

contains "more than"

right-tailed

It becomes progressively easier to declare statistical significance as we increase what?

sample size

Constructing a testable hypothesis is one step in the _____ ______.

scientific method

Sociologists want to test whether the number of homeless people in a particular urban area is increasing. In 2010, the average number of homeless people per day who sought shelter was 42.3 (σ = 6.2). Data from the current year reveal that the mean number of people seeking shelter per day is 45.3. What is the correct statistical test?

single sample z test

Researchers report that, on average, freshmen who live on campus gain 15 pounds during their first year in college. You survey 10 of your friends and find that the average weight gain in the first year was 16.2 lbs (s.d. = 2.6). How does weight gain among your friends compare to the national average? What is the correct statistical test?

single-sample t-test

factors affecting power

size, significance level, true value of the parameter being tested

directional hypothesis

states that one measure will be more than or less than a comparison measure, specifies the direction of the expected difference

non-directional hypothesis

states that two measures will be different from each other, but does not specify the direction of the difference

A researcher is interested in whether the reaction time (RT) to a signal change of a sample of 24 student drivers is slower (greater RT) than the RT published in a news report.

t test, right-tailed

single-sample t-test for means

t= (x bar - mu)/ (s/ sq rt n)

rejection regions

the area that lies beyond the cutoff score in the extreme tail of the distribution

cutoff score

the critical value that marks the boundary of the rejections region

The smaller the degrees of freedom, ________.

the larger the critical t

if the p value of the statistic is less than alpha

the null hypothesis is rejected

In an experimental situation, support is said to accrue to the alternative hypothesis under what condition?

the null is rejected

The alternative hypothesis can never be proved in a single experiment.

true

The p-value of an outcome is the probability of obtaining this result given that the null hypothesis is _________.

true

proof by contradiction

two competing hypotheses are initially proposed, data gathered and statistical tests are carried out, determine which of the two hypotheses can be rejected or supported based on data analysis

contains "not equal to"

two-tailed

null not rejected false

type 2 error, probability= beta

a score that falls in the rejection region is considered

unlikely to have occured if the null hypothesis is true

A sociologist wants to determine how the survival rate for newborns in a small developing country compares to the rate reported by World Health Organization for heavily industrialized countries.

yes

You wonder if the proportion of female to male psychology majors at your university is similar to that found in a national survey of university students.

yes

A clinical psychologist wants to compare the scores of his therapy group of 18 clients on a measure of self-confidence to the results in a published paper that includes the mean and standard deviation.

z test, two-taile

Your university is upgrading the computers on campus. A national student survey revealed that 62% of college students preferred PCs to Macs. A recent poll of 200 social science majors at your university revealed that 82% of students preferred Macs to PCs. How do social science majors at your university compare to national Mac computer preference norms for college students? What is the correct statistical test?

z-test for proportions

signle sample z test for proportions

z= (p hat - p)/ sq rt (pq/n)

Single-sample z test for mean

z= (x bar - mu)/ (standard deviation/ sq rt n)