Questions and Answers of Introduction To Statistical Investigations

Researchers in Australia (Rogers et al., 2019) investigated whether tattoos affect sweat rates when exercising. They recruited 22 subjects, each with a tattoo that was more than 2 months old, larger
Recall Exercise 7.2.40 on the effect of music on chimpanzees. The researchers also kept track of the total number of aggressive events each chimpanzee displayed and divided these by the total time
Reconsider Exercises 7.2.37 and 7.2.38 on time headway variability. If you haven’t done so, put the data file TimeHeadwayVariability in the Matched Pairs applet and do at least 1,000
Reconsider Exercise 7.2.37 on time headway variability. If you haven’t done so, copy and paste the data from the file TimeHeadwayVariability into the Matched Pairs applet and do at least 1,000
Recall Exercises 7.2.33, 7.2.34, and 7.2.35 in which researchers explored the effects on driving with various types of cell phone use. In particular, they were interested in comparing the effects of
Recall Example 7.3 about adding a laugh track to dad jokes to make them funnier. The researchers investigated two kinds of laugh tracks—one with posed laughter and one with spontaneous laughter.
Reconsider Exercises 7.2.33 and 7.2.34 on braking reaction time. If you haven’t done so, put the data file BrakeReactionTime in the Matched Pairs applet and do at least 1,000
Reconsider Exercise 7.2.33 on braking reaction time. If you haven’t done so, put the data file BrakeReactionTime in the Matched Pairs applet and do at least 1,000 randomizations. a. What is
A study done by Jung et al. (2014) looked at hurricane names and the perceived threat. The researchers thought that hurricanes in the United States with male names would differ in perceived danger
Researchers at Arizona State University (McNabb & Gray, 2016) explored the effects on driving with various types of cell phone use. In particular, they were interested in comparing the effects
Student researchers wanted to see whether listening to music with lyrics would affect a person’s ability to memorize words compared to listening to music without lyrics. They recruited 31 people
Student researchers wanted to explore whether a person’s ability to memorize objects is affected by whether they are shown the objects in pictures that are in color or pictures in black and white.
Reconsider Exercise 7.2.18 about rating bottled and tap water. a. Use the 2SD method to determine an approximate 95% confidence interval for the mean difference in water ratings (bottled –
Recall Exercise 7.3.30 about music and the Stroop test. a. Put the data into the Matched Pairs applet to find the sample mean, sample standard deviation, and sample size of the
Is a basketball player’s ability to make free throws different when they get their own rebound or when someone else gets their rebound for them? This is what student researchers wanted to explore.
Do people think bottled water tastes better than tap water? In a blind taste test, student researchers asked 31 subjects to rate the taste of two waters, one bottled and one tap, on a scale from 1 to
When you hand in your test, do you think you will get a higher score than you actually do? A professor collected data to answer this question in a college mathematics course. After finishing a test,
Student researchers wanted to see whether listening to music would affect the time it takes people to complete a Stroop test. In a Stroop test, words of colors are shown printed in a color that does
Suppose your research question is: Can people better memorize 10 objects if they are shown the objects in pictures or in words? Describe how you could set up and run an experiment to answer this
Reconsider Exercise 7.2.16 about rebounding free throws. a. Use the 2SD method to create an approximate 95% confidence interval for the mean difference in number of shots made (rebounded –
Which of these is the correct way to calculate the standardized test statistic for a one-sample t-test for paired data with x?d = 2.3, sd = 1.8, and n = 35?A.B.c.D.E. t= 2.3 1.8/√/35
In Exercise 7.2.13 the statistic used was the mean of the difference in ages (husband’s age − wife’s age). Explain how the following things would change (or not) if you used the mean of the
Which of these is an appropriate way to write out the null hypothesis in symbols for a test for paired data with a quantitative response? A. H0: x?d = 0 B. H0: p?d = 0 C. H0: πd =
With paired data: A. The mean of differences is always the same as the difference of the two group means, and the standard deviation of the differences is always the same as the difference of
The following set of dotplots with overlaid boxplots gives the cost of the most recent haircut for 20 male college students (top) and 20 female college students (bottom) in a statistics class. The
For which of these would you, most likely, want to use a paired design for the study? A. Compare males and females on how many Facebook friends they have B. Compare the income levels of
Suppose you are calculating a 95% confidence interval for the mean difference using paired data to compare the number of words memorized by people while listening to music compared to the number of
Suppose you plan to conduct an experiment to compare reaction times when getting a visual cue versus an auditory cue. Your friend wants to test 40 people, 20 under each condition (randomly deciding
Which of these is the correct way to calculate an approximate 95% confidence interval for the mean difference based on paired data with x?d = 3.5, sd = 2.4, and n = 40? A. 2.4 ± 2(3.5/
Suppose you are testing the hypotheses H0: μd = 0 and Ha: μd ≠ 0 in a paired-design and obtain a p-value of 0.21. Which one of A–D could be a possible 95% confidence interval for μd?A. −2.30
Student researchers at Hope College conducted an experiment to determine whether there is a difference in memorization ability of students when they take notes on paper using handwriting versus
Recall Exercise 6.2.37 on inhibitory control. Besides keeping track of the total time it took the animals to reach the food, the researchers also kept track of the amount of time the animals spent at
The following set of dotplots with overlaid boxplots gives the number of pairs of flip-flops students said they owned for 13 males (top) and 37 females (bottom) in a statistics class. The five-number
Student researchers tested to see whether listening to music while memorizing words would interfere with a person’s ability to memorize words. Their subjects were randomly assigned to either listen
Researchers Marshall-Pescini et al. (2015) compared identically raised pack dogs and wolves on inhibitory control. To do this, a v-shaped fence constructed of wire mesh was set up with a food item (a
Researchers Chaddock-Heyman et al. (2015) investigated the role of aerobic fitness in mathematical achievement in preadolescent children. They had 24 children in their high fitness group (>70th
Recall Exercises 6.2.34 and 6.2.35 about comparing distances traveled by captive African and Asian elephants. a. Put the data in the Multiple Means applet to create a null distribution and from
A study done by Jung et al. (2014) looked at hurricane names and their perceived threat. They thought that if hurricanes in the United States had male names they would be perceived as more dangerous.
Statistics students wanted to see whether there was an association between whether students eat breakfast daily and their grade point average (GPA). They surveyed 106 students at their college and
Recall Exercise 6.2.34 about comparing distances traveled by captive African and Asian elephants. a. Put the data in the Multiple Means applet to create a null distribution and from it calculate
Listed below are the number of cups of coffee 25 students in a college statistics class said they drink per week. 1, 14, 4, 13, 10, 14, 10, 5, 18, 21, 26, 20, 10, 6, 1 ,7, 10, 1, 12, 2, 3, 16,
Similar to Exercise 6.3.33, researchers Dumas and Dunbar wanted to compare creativity of students with different majors at their university, specifically biology and theater. As a measure of their
Researchers Holdgate et al. (2016) studied walking behavior of elephants in North American zoos to see whether there is a difference in average distance traveled by African and Asian elephants. They
Researchers Dumas and Dunbar wanted to see whether stereotypes related to creativity can influence the creativity of a subject (2016). The 64 subjects were randomly placed into two groups of 32 each.
Recall Exercises 6.2.31 and 6.2.32 about memorizing words by a group that was listening to music compared to a group that was not listening to music. a. Put the data in the Multiple Means applet
a. Construct a 95% confidence interval for the difference in the mean evacuation ratings between the female-named hurricane (Christina) and the male-named hurricane (Christopher) and describe what it
Recall Exercise 6.2.31 about memorizing words by a group that was listening to music compared to a group that was not listening to music.a. Put the data in the Multiple Means applet to create a null
A study by Junget al. (2014) looked at hurricane names and their perceived threat. They thought that if hurricanes in the U.S. had male names they would be perceived as more dangerous. In one part of
Student researchers tested to see whether listening to music would interfere with a person’s ability to memorize words. Their subjects were randomly assigned to either listen to music or not. They
Reconsider Exercises 6.3.26–6.3.29. a. If the sample responses had shown more variability in each group (say, SD of 2 in each group) and all else had remained the same as originally, what
Recall Exercises 6.2.28 and 6.2.29 about comparing quiz scores between students taking notes on paper versus the computer. a. Put the data in the Multiple Means applet to create a null
Reconsider Exercise 5.CE.16. Using the same data but grouping “routine” with “exciting” rather than with “dull” produces the following 2 × 2 table: Analyze these data to investigate
Recall Exercise 6.2.28 about comparing quiz scores between students taking notes on paper versus the computer. a. Put the data in the Multiple Means applet to create a null distribution and from
Student researchers at Hope College conducted an experiment to determine whether students memorize material better if they are taking notes on paper using handwriting as opposed to taking notes on a
An article that appeared in the British Medical Journal (2010) presented the results of a study conducted by researcher Jeremy Groves, whose objective was to determine whether the type of frame of
For Exercise 6.1.19 on students sending texts, are there any outliers in the distribution according to the 1.5 × IQR rule? If so, which ones? Data from Exercise 6.1.19Twenty college students
Twenty college students were asked how many texts they send on a typical day and the results are shown below. 3, 4, 5, 10, 10, 10, 20, 20, 30, 30, 30, 50, 50, 55, 75, 75, 100, 150, 200,
The 2020 U.S. Senate consists of 75 men and 25 women. The 2020 U.S. Senate consists of 53 Republicans and 47 Democrats (counting 2 Independents as Democrats because they vote with Democrats more than
What are the five parts of the five-number summary?
Research on reducing stuttering in preschool children between the ages of 3 to 6 looked at 199 children who were registered in one of 20 participating speech therapy clinics throughout the
Refer to Exercise 5.2.43. Redo parts (d), (e), and (f) using the relative risk as the test statistic. Data from Exercises 5.2.43Are there differences in the efficacy of duct tape versus
Reconsider Exercise 5.1.16, along with this additional information: 17 senators are women Democrats. a. Produce a 2 × 2 table that classifies senators in the 2020 U.S. Senate according to party
The U.S. government authorizes private contractors to audit bills paid by Medicare and Medicaid. The contractor audits a random sample of paid claims and judges each claim to be either fully
Consider the four 2 × 2 tables, numbered 1–4. For each one the response is Yes/No and the explanatory variable is A/B a. Which two tables have the same pair of conditional
Data were gathered on 106 statistics students from a Midwestern college on variables including the sex of the respondent and whether they had eaten breakfast that morning. Which segmented bar graph
Suppose you are getting ready to run a two-proportion z-test to see whether students who have studied statistics are more likely to always wear seat belts in a car than those who haven’t studied
Using data from Exercises 5.2.3 and 5.2.4, use the Multiple Proportions applet to carry out a test of significance. Which of A–D is an approximate 2SD confidence interval? A. 0.082 to
Describe the parameters of interest in words. (You can use the symbol π to represent these parameters.)In 1970 Linus Pauling, a well-known chemist and Nobel Prize winning scientist, published
Using data from Exercise 5.2.3, which of A–D is the correct value for the appropriate statistic? A. 0.15 B. 0.25 C. 0.325 D. 0.40Data from Exercise 5.2.3Suppose you sample from
Which of A–D answers correctly calculates the relative risk for success in Group A compared to Group B (p?A/p?B) for the two-way table below?A. (10/60)/(20/60) = 1/2 B. (10/20)/(20/40) =
What are the variables that are measured/recorded on each unit?In 1970 Linus Pauling, a well-known chemist and Nobel Prize winning scientist, published Vitamin C and the Common Cold (1970), creating
Suppose you sample from two large populations and find sample proportions of p?1 = 120/300 and p?2 = 125/500. Suppose you are going to complete a test of significance using these proportions to see
What are the observational/experimental units?In 1970 Linus Pauling, a well-known chemist and Nobel Prize winning scientist, published Vitamin C and the Common Cold (1970), creating a great deal of
Suppose a 95% confidence interval for the difference in the proportion of female students who regularly drink coffee and the proportion of male students who regularly drink coffee (πF – πM) is
Which of A–D answers correctly calculates the difference in the proportions of success for Group A compared to Group B (p?A – p?B) for the two-way table below? A. (10/60) – (20/60) B.
Is this study an experiment or an observational study? How are you deciding?In 1970 Linus Pauling, a well-known chemist and Nobel Prize winning scientist, published Vitamin C and the Common Cold
Which type of distribution is used in a two-sample z-test? A. t-distribution B. Normal distribution C. Simulated null distribution D. Double proportion distribution E. None
Suppose you are testing to see whether the proportion of males who voted in the last election differs from the proportion of females who voted in the last election. Which of these is NOT a correct
Journal articles that describe some randomized experiment often include a table of the characteristics of the subjects after they were randomly assigned to the treatments, but before the treatments
State the research question. In 1970 Linus Pauling, a well-known chemist and Nobel Prize winning scientist, published Vitamin C and the Common Cold (1970), creating a great deal of public and
The validity conditions for a two-sample z-test include: A. You should have at least 10 successes and 10 failures in each group. B. Each group should have a sample size of at least
Student researchers at Hope College were interested in cell phone usage by students on campus and how it varied during different times of the day. They observed students walking around campus, 232
In Exploration 4.2 you used the Randomizing Subjects applet to randomly assign subjects to two groups. At the end of the exploration, you blocked on a person’s sex and saw this eliminate the
Crohn’s disease involves chronic inflammation anywhere in the gastrointestinal (GI) tract. The disease is subdivided by where it occurs in the GI tract. Suppose a company is testing a new
Do your bananas get over-ripe too fast? It has been said that if you wrap the stem of a banana in plastic, it will last longer. A student experiment seeks to explore whether this is true. They bought
Are there side effects of watching 3D movies? More specifically, is nausea a side effect? A study done in Italy (Solimini, 2013) had moviegoers rate their levels of nausea on a 7-point scale after
Butterfat is the fat that naturally occurs in cow’s milk. For a product to be labeled whole milk, for example, it must contain at least 3.25% butterfat. Does the amount of butterfat vary with
The Physicians’ Health Study II was a randomized, double-blind, placebo-controlled study designed to “test alternate-day beta-carotene, alternate-day vitamin E, daily vitamin C, and a daily
The Physicians’ Health Study I was a very large, randomized, double-blind, placebo-controlled study designed to “test the effects of low-dose aspirin and beta-carotene on cancer and
Hurricanes in the United States are given names. Since 1979 both male and female names have been used, alternating between names that are typically thought of as male and those typically thought of
Students completing a project for their statistics class were testing whether, when blindfolded, subjects would be more likely to identify the flavor of an orange Starburst or a lemon Starburst. The
A drug manufacturer is testing a new headache drug. They recruit 100 subjects with headaches and have them rate the severity of their headaches on a scale of 1 to 10. The researchers randomly assign
A drug manufacturer is testing a new headache drug. They recruit 100 subjects with headaches and have them rate the severity of their headaches on a scale of 1 to 10. Based on the severity of the
A drug manufacturer is testing a new headache drug. They recruit 100 subjects with headaches and have them rate the severity of their headaches on a scale of 1 to 10. They give them the new drug and
Student researchers want to see whether students retain information better when they are taking notes by hand (with pen and paper) than on the computer, as some research suggests. Suppose they have
Causation. Is a cause-effect conclusion possible in this new study? Why or why not?The hypotheses are modified slightly for this new study: Null: The long-run proportion of men who will call the
To investigate whether there is an association between happiness and income level, we will use data from the 2018 General Social Survey (GSS), cross-classifying a person’s perceived happiness with
Fill in the two-way table with the data from the study.how to state null and alternative hypotheses for studies like this. Here they are for this study: Null: The long-run proportion of men who
A Pew Research Center poll conducted in 2017 found that 49% of respondents who were 65 years or older often get their news from network TV compared to 8% of 18- to 29-year-olds. a. Identify the
Which of the following are experiments? 1. Researchers ask subjects whether they drink coffee regularly and how much sleep they get per night to see whether there is an association between

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