Sampling error is defined as:

|x |

N-n

/n

Question 3

Simple random sampling is a method of sampling that allows each possible sample of size n an equal probability of being selected.

True

False

Question 4

If the sampling distribution of the sample means approximates a normal distribution, then the population must be normally distributed.

True

False

Question 5

When the sample population is skewed, the sample size must be at least 15 before the sampling distribution of becomes approximately normal.

True

False

Question 6

This table represents the first 7 observations from a sample of 200 individuals, who reported their age, race, income, and job satisfaction score on a scale from 0 to 100. Based on the table, which of the following best describes the Income variable?

Age	Race	Income	Score
33	B	$20,000-23,000	32
41	B	more than $100,000	84
26	A	$30,000-40,000	78
22	O	$10,000-20,000	87
19	A	$40,000-50,000	42
34	W	$50,000-60,000	21
26	W	less than $10,000	91

categorical, ordinal

categorical, dichotomous

quantitative, continuous

quantitative, discrete

Question 7

This table represents the first 7 observations from a sample of 200 individuals, who reported their age, race, income, and job satisfaction score on a scale from 0 to 100. Which type of plot would be most useful for visualizing the relationship between Age and job satisfaction Score?

Age	Race	Income	Score
33	B	$20,000-23,000	32
41	B	more than $100,000	84
26	A	$30,000-40,000	78
22	O	$10,000-20,000	87
19	A	$40,000-50,000	42
34	W	$50,000-60,000	21
26	W	less than $10,000	91

scatter plot

histogram

single box plot

bar chart

Question 8

A student is gathering data on the driving experiences of other college students. A description of the data is presented below. Which of the variables are quantitative and discrete?

car: 1 = compact, 2 = standard size, 3 = mini van, 4 = SUV, and 5 = truck

color: red, blue, green, black, white

daysDrive: number of days per week the student drives

gasMonth: the amount of money the student spends on gas per month

daysDrive

car

daysDrive, car

daysDrive, gasMonth

Question 9

The alumni association for our college has gathered a large dataset on graduating seniors. Some of the variables in the data set are gender, major, GPA, and starting salary. They are interested in looking at relationships among these variables. For which of the following pairs of variables would a two sample t-test be appropriate to examine whether there is a relationship between the two variables?

GPA and salary

GPA and gender

gender and major

none of these

Question 10

Suppose we examine the distribution of scores on the last exam separately for freshman and sophomores. Both distributions are approximately normally distributed and have the same mean, but the distribution of exam scores had a smaller standard deviation among sophomores than freshman. A z-score is calculated for Mary's exam score relative to both distributions (freshman and sophomores). Given that Mary's score is well above the mean, which of the following would be true about these two z-scores?

The z-score based on the distribution for the sophomore students would be higher.

The z-score based on the distribution for the freshman students would be higher.

The two z-scores would be the same.

There is not enough information to determine.

Question 11

A statistician working for the Frisco Police Department believes that the proportion of reported car accidents involving cell phone use in Atlanta differs from the national reported proportion of 26%. Suppose that, from a sample of 500 accident reports, she finds 120 cases of auto accidents that involved the use of cell phones. At the 0.01 level of significance, which of the following statements provides the best conclusion based on her test results?

We do not have sufficient evidence to conclude that the true percent of car accidents involving cell phone use differs from 26%.

We have evidence the true percent of car accidents involving cell phone use is greater than 26%.

We have evidence the true percent of car accidents involving cell phone use is equal to 26%.

We have evidence the true percent of car accidents involving cell phone use is less than 26%.

Question 12

A z-statistic is used for a problem involving any sample size and an unknown population standard deviation.

True

False

Question 13

What is the interpretation of a 90% confidence level?

Approximately 90 out of 100 such intervals would include the true value of the population parameter.

The interval contains 90% of all sample means.

There's a 10% chance that the given interval does not include the true value of the population parameter.

There's a 90% chance that the given interval includes the true value of the population parameter.

Question 14

What does the assumption of independence mean?

This assumption means that the errors in your model are not related to each other.

This assumption means that the residuals in your model are not independent.

This assumption means that you must use an independent design rather than a repeated-measures design.

This assumption means that none of your independent variables are correlated.

Question 15

In which of the following situations is the assumption of normality least important?

If you have a small sample.

If you want to construct confidence intervals around the parameter estimates of your model.

If you want only to estimate the parameters of your model.

If you want to compute significance tests relating to the parameter estimates of your model.

Question 16

A researcher conducts some research in which they identify a significant positive correlation (r = .42) between job satisfaction and manager competency (both measured on a rating scale). Which of the following is an inappropriate conclusion?

More satisfied employees have incompetent managers.

That improved manager competency makes employees more satisfied with their job.

That the consequences of having more competent managers are unclear.

That it is possible to predict someone's job satisfaction based on their opinion towards the competency of their manager.

Question 17

You generate a Pearson's correlation coefficient to assess whether shareholder value is correlated with the number of employees hired at law firms. Which of the following statement is not accurate when employing this test?

It cannot be used with binary variables (those taking on a value of 0 or 1).

It can be used to measure 'effect size'.

It can be used on ranked data.

It varies between -1 and +1.

Question 18

The central limit theorem tells us:

If the sample is large enough, the sampling distribution of a parameter will be approximately normal.

If the sample is large enough we can assume homogeneity of variance.

In small samples, significance tests can't be trusted.

In small samples, the assumptions of parametric tests matter less.

Question 19

The correlation between employee IQ and productivity in a factory is .72 with a significance of p < .01. What can we conclude?

That there is a substantial relationship between IQ and productivity.

That there is a small relationship between IQ an productivity.

That IQ causes productivity.

That productivity results in higher IQ.

Question 20

Which of the following statements is inconsistent with the Central Limit Theorem?

1 point

The Central Limit Theorem applies without regard to the size of the sample.

The Central Limit Theorem applies to non-normal distributions.

The Central Limit Theorem indicates that the sampling distribution will be approximately normal.

The Central Limit Theorem indicates that the mean of the sampling distribution will be equal to the population mean.

Question 21

When a variable follows a normal distribution, what percent of observations are contained within 1.75 standard deviations of the mean?

91.88%

4.01%

9.02%

68.26%

Question 22

A researcher wants to determine if a new treatment is effective for reducing COVID related fever. What type of study should be conducted in order to establish that the treatment does indeed cause improvement in COVID patients?

Identify COVID patients who received the new treatment and those who did not, and then compare the fever of those two groups.

Randomly assign COVID patients to one of two groups, either the treatment or placebo group, and then compare the fever of the two groups.

Identify clusters of communities and then stratify them by gender and compare the fevers of male and female groups.

Both studies (a) and (b) can be conducted in order to establish that the treatment does indeed cause improvement with regards to fever in COVID patients.

Question 23

Rhesus monkeys kept in captivity are given a range of items in their living areas for enrichment, and the managers of these captive groups conduct a variety of experiments to see what setups are most beneficial to the monkeys. In which scenario would it be appropriate to conduct analysis of variance (ANOVA)?

Researchers divide monkeys into four groups, each group with a different enrichment setup. After one week, blood samples are collected to measure stress hormone levels, and the researchers are interested in seeing if the mean stress levels differ amongst the groups.

Researchers collect baseline levels of stress hormones from one group of monkeys with no enrichment. After this baseline measurement, researchers add a climbing toy to the living area. After one week, they collect another hormone sample from the same monkeys and want to compare the baseline levels to the post-enrichment levels.

Researchers collect behavioral data on monkeys and categorize them as either "high stress" or "low stress." They also have information on what their enrichment classification is in their group (food-focused, toy-focused, or structure-focused). They are interested in seeing if there is an association between the monkeys' stress category and enrichment classification.

Researchers collect behavioral data on monkeys and categorize them as either "high stress" or "low stress". They are interested in seeing if the proportion of high stress monkeys is significantly different in a group with toy-focused enrichment compared to a group with food-focused enrichment.

Question 24

In a given one-sample t-test, the test statistic is found to be 1.80. The student who conducted the test concludes that he should fail to reject the null hypothesis. Which of the following scenarios does not justify the student's decision?

All of these scenarios would justify the fail to reject H0 decision.

df = 10, = 0.01, and a one-sided greater than alternative hypothesis.

df = 60, = 0.05, and a two-sided alternative hypothesis.

df = 10, = 0.05, and a one-sided greater than alternative hypothesis.

Question 25

A random variable represents the outcome of an experiment.

True

False