Q1

4 Points

A 2017 study examined a large sample of health records from a California health insurance for children born between 2000-10. The study found that 3103 children had a diagnosis of autism spectrum disorder (ASD) and the remaining 193,826 did not. Below is a summary table from the publication.

Q1.1

2 Points

The value 82% listed in this table is part of:

Choice 1 of 4:The conditional distribution of ASD diagnosis, given sexChoice 2 of 4:The conditional distribution of sex, given ASD diagnosisChoice 3 of 4:The marginal distribution of ASD diagnosisChoice 4 of 4:The marginal distribution of sex

Q1.2

2 Points

How common was an ADS diagnosis among the girls in this study? Give your answer as a percentage rounded to 1 decimal place, for ex. 11.1%. (Do include the % symbol but do not spell it out or add text.)

Q2

4 Points

A 2012 study of freely forming groups in bars all over Europe examined the natural behavior of groups. The researchers recorded the group size (number of individuals in the group) of all 501 groups in the study that were naturally laughing. The findings were displayed in the figure below.

Q2.1

2 Points

Complete this summary sentence by filling in the blanks with numerical values rounded to one decimal place if needed (for ex., 1.1, no text or units).

For groups in European bars observed to be naturally laughing before the pandemic (in 2012), group size ranged from a minimum of

to a maximum of

with a median size of

Q2.2

2 Points

Can we conclude from these findings that smaller groups are more likely to be laughing than larger groups? Explain your reasoning in one short sentence.

Q3

4 Points

A 2015 study examined whether light-emitting eReaders at bedtime may impair sleep quality. A random sample of 12 healthy adults slept in the lab on two different days. In random order, participants read for 30 minutes a print book one night and a light-emitting eReader the other night. Scalp electrodes were used to measure how long (in minutes) it took participants to reach a deep sleep stage. On average, the subjects took 12.3 minutes longer to reach deep sleep with the eReader than with the book.

Q3.1

2 Points

Choose the appropriate layout to record data from this study.

Choice 1 of 2:Table AChoice 2 of 2:Table B

Q3.2

2 Points

On average, it took healthy adults longer to reach deep sleep when they used an eReader compared to a print book (a “significant,” surprisingly substantial, difference). What conclusion can we draw from this study?

Choice 1 of 3:We cannot conclude that the significant increase in time to deep sleep is caused by the eReader because the study didn’t include people who do not read books.Choice 2 of 3:Because of the experimental design, we can conclude that the use of an eReader is the reason for this significant increase in time to deep sleep.Choice 3 of 3:Because participants were simply observed while sleeping, the significant increase in time to deep sleep may or may not be caused by the use of an eReader.

Q4

6 Points

In 2018, the data analytics website, The Pudding, published an analysis of men’s and women’s pocket sizes for the most popular American brands of blue jeans. Download the data file below:
https://drive.google.com/file/d/14IT82MGQ6MnLct9ao04BHT6cMldwF5fb/view?usp=sharing
(This file, jeans-pockets2018.csv, is also accessible from Canvas on the Topic 2 Roadmap.) Import this data file into CrunchIt: http://crunchit3.bfwpub.com/psls4e

We will look at the price (in dollars, $) of men’s and women’s jeans. This corresponds to the variables “price” and “menWomen” in the data file.

Q4.1

2 Points

Plot the data for men’s and women’s jeans prices in a side-by-side boxplot. Be sure to label both axes of your graph and include units as needed. Set the title to be your first and last name — understand that you will not get full credit unless your graph has your name in its title. Right-click on your graph to “save as image” on your desktop, then upload this image here.

Please select file(s)Select file(s)

Q4.2

2 Points

Obtain the 10th percentile of prices for women’s jeans. Enter this value rounded to the nearest dollar (for ex., 11, no text or symbol).

Q4.3

2 Points

The 10th percentile of prices for women’s jeans indicates that 10% of women’s jeans in the data set are

Choice 1 of 3:at least as expensive as that value.Choice 2 of 3:at most as expensive as that value.Choice 3 of 3:roughly equal in price to that value.

Q5

2 Points

National College Athletic Association (NCAA) provides data on college sports injuries. When an injury occurs, the NCAA adds an entry to their database. The database does not track which player experienced the injury.

This figure below summarizes all injuries experienced by women’s collegiate volleyball players from 2005 to 2009. It shows what percent of all injuries were of each type. Injury types that made up less than 2% of all injuries were grouped together as “All other.”

Consider these two statements summarizing the findings:
A) Between 2005 and 2009, the most common type of injury reported by women collegiate volleyball players was a sprain.
B) Between 2005 and 2009, nearly half of all women collegiate volleyball players experienced either a sprain or a muscle tear.

Choice 1 of 4:A is incorrect but B is correct.Choice 2 of 4:A is correct but B is incorrect.Choice 3 of 4:Both A and B are incorrect.Choice 4 of 4:Both A and B are correct.

Q6

2 Points

A study assessed the effects of playing a computer game (solitaire) during lunch on snack behavior. A sample of 44 healthy adults was randomly assigned to eat lunch either with the computer game distraction or without distraction. All participants ate the same breakfast and lunch.

Thirty minutes after lunch, participants were offered cookies as a snack and were instructed to eat as many or as few cookies as they liked. Those who ate with the distraction ate on average 52 grams of cookies, compared with 27 grams for those who ate without the distraction — a surprisingly substantial (statistically significant) difference.

What can we reasonably conclude from this study?

Choice 1 of 5:Because of confounding variables, we cannot conclude that a computer distraction necessarily leads to higher snack intake.Choice 2 of 5:Because of confounding variables, we cannot conclude that a computer distraction necessarily leads to higher snack intake, on average, in lab situations offering free food.Choice 3 of 5:In similar lab situations offering free food, eating with a computer distraction leads healthy adults to snack more later, on average.Choice 4 of 5:In similar lab situations offering free food, eating with a computer distraction leads all healthy adults to snack more later.Choice 5 of 5:Eating with a computer distraction leads all healthy adults to snack more later.

Q7

2 Points

New York State (excluding New York City) reported the deaths of all white men and black men who died from prostate cancer (PC) in 1994. The data are summarized below.

Overall, the death rates from prostate cancers were very similar for White men and Black men in New York State in 1994. This fact, however, obscures some stark differences between White men and Black men, where Black men clearly suffered disproportionately from prostate cancer. This paradox is due to the fact that

Choice 1 of 4:the percent of white men was higher among the older men than among the younger men, and older men were more likely to die.Choice 2 of 4:the percent of white men was higher among the younger men than among the older men, and older men were more likely to die.Choice 3 of 4:the percent of white men was higher among the older men than among the younger men, and older men were less likely to die.Choice 4 of 4:the percent of white men was higher among the younger men than among the older men, and older men were less likely to die.

Q8

4 Points

A study published in 2015 examined material-need insecurities (food insecurity, cost-related medication underuse, housing instability, and energy insecurity) among adults diagnosed with diabetes. The study collected data on a random sample of 411 adult diabetic patients treated in medical centers all over Massachusetts. It found that 64.1% of the patients who experienced food insecurity had a poor control of their diabetes, whereas 41.6% of the patients who didn’t experience any food insecurity had a poor control of their diabetes.

Q8.1

2 Points

Which of the following plots correctly displays the reported study findings?

Choice 1 of 3:Choice 2 of 3:Choice 3 of 3:

Q8.2

2 Points

What would be an appropriate conclusion from this study?

Choice 1 of 4:In Massachusetts, experiencing food insecurity interferes with adult diabetic patients’ ability to control their diabetes.Choice 2 of 4:Experiencing food insecurity interferes with adult diabetic patients’ ability to control their diabetes.Choice 3 of 4:There is a link between food insecurity and diabetes control among adult diabetic patients in Massachusetts, but it is not necessarily a causal link.Choice 4 of 4:There is a link between food insecurity and diabetes control among adult diabetic patients, but it is not a causal link.

Q9

6 Points

The pulse oximeter is an inexpensive and non-invasive device that assesses a person’s blood oxygen level (“oxygen saturation”) by shining light through the skin of a finger. It is commonly used to determine whether a COVID-19 patient should be admitted to the emergency room and how much oxygen to give them.

A 2020 study compared the reading from a pulse oximeter with the actual oxygen level in blood drawn from an artery, in a large sample of hospitalized patients who identified their race as Black or White. The findings are summarized in the figure below. The figure highlights the arterial oxygen saturation value 88% because of its clinical relevance in a number of medical decisions.

Q9.1

2 Points

Select the best option from the listed choices to fill in the “BLANKS” in the following sentence:

Among patients with a pulse oximeter reading of 91%, BLANK-1 of White patients and BLANK-2 of Black patients had actual arterial oxygen saturations below the 88% level.

BLANK-1:

Choice 1 of 4:less than one quarterChoice 2 of 4:less than halfChoice 3 of 4:more than halfChoice 4 of 4:more than three quarters

BLANK-2:

Choice 1 of 4:less than one quarterChoice 2 of 4:less than halfChoice 3 of 4:more than halfChoice 4 of 4:more than three quarters

Q9.2

2 Points

The pulse oximeter performed worse overall for Black patients than for White patients, with data showing a tendency of the device to

Choice 1 of 2:overestimate (inflate) the true arterial blood oxygenation level of Black patients.Choice 2 of 2:underestimate (understate) the true arterial blood oxygenation level of Black patients.

Q9.3

2 Points

In the article, the researchers stated that “Questions about pulse oximeter technology have been raised, given its original development in populations that were not racially diverse.”

To what statistical issue does this statement refer?

Choice 1 of 7:BlindingChoice 2 of 7:Nonresponse biasChoice 3 of 7:Response biasChoice 4 of 7:The placebo effectChoice 5 of 7:UndercoverageChoice 6 of 7:Voluntary response biasChoice 7 of 7:Wording effects

Q10

2 Points

A study of the effect of vitamin E on vascular disease in smokers recruited 22 healthy young adult male smokers and randomly assigned them to take for four weeks either a vitamin E supplement pill or an identical-looking pill containing no vitamin E. The study used ultrasound to measure the participants’ arterial diameter (in millimeters) at the end of the study. The ultrasound operator was not told which participant had taken the vitamin E supplement.

Explain why this study does not have a case-control design.

Choice 1 of 4:Although this and a case-control study are both randomized experiments, in a case-control study we take two random samples (one of cases and one of controls) whereas here we have only one.Choice 2 of 4:Although this and a-case control study are both observational studies, in a case-control study we take two random samples (one of cases and one of controls) whereas here we have only one.Choice 3 of 4:A case-control study is a type of experiment where we take two separately acquired random samples (one of cases and one of controls); here we have data on only one random sample of participants and it is a cross-sectional observational study.Choice 4 of 4:A case-control study is a type of observational study where we take and compare two separately acquired random samples (one of cases and one of controls); here we have only one sample of participants who were randomly assigned to the conditions, which means it is a completely randomized experiment.

Q11

9 Points

Manatees are large aquatic mammals that were listed until recently as an endangered species in the United States. Florida has collected census data on manatee deaths for all years since 1977, except for 2020 when data collection was interrupted by the pandemic.

Download the manatee-deaths2019.csv data file at
https://drive.google.com/file/d/1fokbY784GSWN4xC4jvdPd62UoeT4x9wf/view?usp=sharing
containing the number of manatees that died because of a powerboat collision and the number of powerboats registered (recorded in thousands) in any given year in Florida between 1977 and 2019. (Beware that this file is different from the one posted on Topic 3 Roadmap because it has one more row.)

You can upload the data into CrunchIt (http://crunchit3.bfwpub.com/psls4e) either from the ‘Menu / File / Import from file’ or from the ‘Menu / Edit / Paste Spreadsheet’ options.

Q11.1

2 Points

Create a scatterplot of the number of manatees that died because of a powerboat collision and the number of powerboats registered (in thousands) in any given year in Florida between 1977 and 2019. Be sure to properly label the axes and include units as needed. Also enter your first and last name in the title of the graph — understand that you will not get full credit unless your graph has your name in its title. Right-click on your graph to “save as image” on your desktop, then upload this image here.

Please select file(s)Select file(s)

Q11.2

3 Points

Run a linear regression analysis modeling manatee deaths from collision as a function of thousand powerboats registered. In one sentence, interpret the value of the slope in context.

Q11.3

2 Points

Enter the numerical value of $r^2$r2 as a number between 0 and 1 rounded to 2 decimal places (for ex., 0.11, no units, no text or letters).

Q11.4

2 Points

Based on this linear regression model, if Florida were to limit to 700,000 the number of powerboats registered in a year, what could we expect the number of manatee deaths due to collisions with powerboats to be in such years? We would expect

Choice 1 of 7:roughly 50 manatee deaths.Choice 2 of 7:roughly 50 manatee deaths, on average.Choice 3 of 7:roughly 106 manatee deaths.Choice 4 of 7:roughly 106 manatee deaths, on average.Choice 5 of 7:roughly 105,644 manatee deaths.Choice 6 of 7:roughly 105,644 manatee deaths, on average.Choice 7 of 7:a completely unknown number of manatee deaths.

Q12

5 Points

Here is a figure from a report by 2014 report by the Pew Research Center based on a random sample of American adults who use the internet.

Q12.1

3 Points

Express the left-most light-blue value on this graph, 22, as a sentence in context.

Q12.2

2 Points

Explain in one sentence why the dark blue bars for male respondents do not add up to 100% in this figure.