Margin of Error

Written Assignment #7: How to evaluate inferential and descriptive statistics

DUE DATE: June 28, 2019 before 11:59 PM.

READING

a. To review what descriptive and inferential statistics are, why they are important to learn, and examples of how they are used:

1. Watch SomaliNew Production’s (2009) video, “Inferential & Descriptive.” 2. Watch Lynda.com’s (2010) video, “Understanding Descriptive and

Inferential Statistics.” 3. Read Laerd Statistics’ (no date) article, “Descriptive and Inferential

Statistics.” 4. Read a section of Wikipedia’s (2017) entry, “Descriptive Statistics.” 5. Read Statistics HowTo’s (2014) article, “Inferential Statistics: Definition,

Uses.”

b. To really make sure you understand the difference between descriptive and inferential statistics and what each is used for, watch StatsLectures (2010) video, “The Basics: Descriptive and Inferential Statistics.”

1. At this point, you should be clear on the difference between descriptive and inferential statistics and the common uses for both types of statistics.

2. If you’re not clear, you might want to re-read the above articles and re- watch the videos.

3. You might also want to review how to write a Five-Paragraph Examples- Style Essay, by re-watching the latter part of “The Five-Paragraph Model”

WRITING ASSIGNMENT

c. Write one five-paragraph Examples-Style essay (using examples) to support the thesis “Descriptive statistics are useful.” Remember that descriptive statistics can be graphs and figures, as well as means and modes.

1. Check your essay to make sure your Introduction Paragraph has a hook and a Thesis Statement.

2. Check your Thesis Statement to make sure that it summarizes your three examples.

3. Check your essay to make sure it has three Supporting Paragraphs. 4. Check each of your three Supporting Paragraphs to make sure each one

has a Topic Sentence, three or so Supporting Sentences, and a Conclusion Sentence.

5. Check your essay to make sure it has a Conclusion Paragraph.

Part 1: Inferential and descriptive statistics

to make sure it has a sentence that restates your Thesis Statement (summarizing your three examples).

d. In the same document as your first essay, write another five-paragraph Examples-Style essay (using examples), this time to support the thesis “Inferential statistics are useful.”

1. Check your essay to make sure your Introduction Paragraph has a hook and a Thesis Statement.

2. Check your Thesis Statement to make sure that it summarizes your three examples.

3. Check your essay to make sure it has three Supporting Paragraphs. 4. Check each of your three Supporting Paragraphs to make sure each one

has a Topic Sentence, three or so Supporting Sentences, and a Conclusion Sentence.

5. Check your essay to make sure it has a Conclusion Paragraph. 6. Check your Conclusion Paragraph to make sure it has a sentence that

restates your Thesis Statement (summarizing your three examples).

7. Save the entire document as a PDF (which should contain two five- paragraph essays) and name the file YourLastname_DescriptiveInferentialEssays.pdf.

8. Upload your document to Course Materials → Writing Assignment #7, Part 1: Descriptive and Inferential Essays

e. If you ever wonder why we repeatedly practice skills, such as writing five- paragraph essays, in different contexts throughout this course, consider the words of William James, who is widely considered the father of modern psychology!

READING

a. To become familiar with some of the ways that descriptive and inferential statistics can be used to deceive people, read Chapters 2 through 6 of (a slender!) book titled How to Lie with Statistics by Darrell Huff.

1. NOTE: This book was published in 1954; therefore, the examples are from the 1940s and early 1950s. However, it’s still a beloved book (e.g., it’s recommended reading in a college physics class), despite its age.

2. Chapter 2 explains the deception caused by indiscriminately referring to the mean, median, and mode (i.e., three central-tendency descriptive statistics) as “the average.”

3. Chapter 3 explains the deception caused by random variation and the solutions provided by inferential statistics.

4. Chapter 4 explains the deception caused by differences that aren’t meaningful.

Part 2: How to lie with statistics

 

b. When reading these chapters, jot down your three favorite deceptions. For example, you might choose as one of your favorite deceptions the hypothetical real estate agent’s deceptive use of a neighborhood’s “average” income in Chapter 2.

WRITING ASSIGNMENT

c. Create a teaching document to teach your three favorite deceptions to other people.

1. You need to choose an audience for your teaching document. Your choices are (1) other college students; (2) middle-school students (age 12 to 14); or (3) older adults (over age 60).

2. You need to choose a medium for your teaching document. Your choices are (1) a powerpoint; (2) an infographic (what’s that?); or (3) a comic strip (e.g., The Nib’s).

3. You need to save your teaching document as a PDF, named YourLastname_StatsDeception.pdf.

d. Save your teaching document to the discussion board forum called “Assignment #7, Part 2: Deception Teaching Document.”

READING

a. To learn what effect size is and why it’s important to report effect size in scientific articles:

1. Read Sullivan and Feinn’s (2012) article, “Using Effect Size—or Why the P Value Is Not Enough.”

2. Sullivan and Feinn’s (2012) article might be harder to read than other articles you’ve read in this course. But try to understand it at least at a superficial level. Feel free to Google terms that you don’t know.

b. To learn how to guard against other trickery with descriptive and inferential statistics:

1. Read Chapman and Louis’s (2017) article, “The Seven Sins of Statistical Misinterpretation.”

2. In contrast to gaining a working, but superficial understanding of the computations and the like that Sullivan and Feinn (2012) provide in their article, make sure you understand well the seven “sins” that Chapman and Louis provide in their article.

Part 3: Other sorts of statistical trickery to watch out for

WRITING ASSIGNMENT

c. Now it’s time to apply Chapman and Louis’s (2017) “Seven Sins of Statistical Misinterpretation” to scientific articles you have read.

1. Choose three of the six articles that you found and read in Assignment #4, Part 1 and synthesized in Assignment #5.

2. Choose the three articles (of your six articles) that will be the easiest (and most logical) to evaluate according to Chapman and Louis’s (2017) “Seven Sins of Statistical Misinterpretation.”

3. Evaluate the three articles by completing this fillable PDF. ▪ First, download the unfilled PDF and save it on your own computer. ▪ Second, rename the unfilled PDF to be YourLastName_PSY430_

StatsCheck_Fillable.pdf. In other words, add your last name to the beginning of the filename.

▪ Third, on your computer, open a PDF writer app, such as Preview, Adobe Reader, or the like. Be sure to open your PDF writer app before you open the unfilled PDF from your computer.

▪ Fourth, from within your PDF writer app, open the unfilled PDF, which you have already saved onto your computer and re-named.

▪ Fifth, using the PDF writer app, fill in the PDF. ▪ Sixth, save your now-filled-in PDF on your computer.

4. There are three pages in the fillable PDF; use a different page for each of your three articles. It’s ok, for this assignment, if you can’t italicize parts of the citation (in the citation text box of the fillable PDF).

d. Go to the discussion board forum “Assignment #7, Part 3: statistical trickery” and attach your filled-in PDF.

READING

a. To answer some of the questions you probably have had about public opinion polls and surveys, read Langers’ (2008) article, “ABC News’ Guide to Polls & Public Opinion.”

1. Make sure you understand the article’s answer to the concern that “[the pollsters] never call me.”

2. Make sure you understand the article’s answer to the concern that “nobody I know says that.”

b. To better understand “margin of error” means in statistics: 1. Read Rumsey’s (no date) article, “How to Interpret the Margin of Error

in Statistics.” 2. Make sure you understand the difference between sampling a population

and surveying (or polling) an entire population.

 

c. To better understand the relation between sample size and margin of error: 1. Read Hunter’s (no date) article, “Margin of Error and Confidence Levels

Made Simple.” 2. Make sure you understand what it means to calculate a margin of error at

a 95% confidence level. 3. Make sure you understand the relation between sample size and margin

of error.

d. Choose three of the following topics for which Gallup has recently conducted a public opinion poll. Then, within each of the three topics you’ve chosen, read one of the listed reports.

1. Employment ▪ Harter and Adkins (2015): “Engaged Employees Less Likely to

Have Health Problems“ ▪ Newport (2017a) “Email Outside of Working Hours Not a Burden

to US Workers“ ▪ Newport and Dugan (2017): “Americans Still See Manufacturing

as Key to Job Creation.” ▪ Newport (2018a): “Average American Predicts Retirement Age

of 66“ ▪ Swift (2017a): “Most U.S. Employed Adults Plan to Work Past

Retirement Age“ 2. Finance

▪ Newport (2017b): “Young, Old in US Plan on Relying More on Social Security“

▪ Jones (2017a): “Worry About Hunger, Homelessness Up for Lower-Income in US“

▪ Norman (2017): “Financially Stressed in US Now Prefer Saving to Spending“

▪ Jones (2017b): “Half of Non-Homeowners Expect to Buy Homes in Five Years“

▪ Newport (2018b): “Americans’ Views of Their Spending and Saving“

3. Well-Being ▪ Rigoni and Nelson (2016): “Millennials Want Jobs That Promote

Their Well-Being“ ▪ Witters (2017a): “Hawaii Leads US States in Well-Being for

Record Sixth Time“ ▪ Witters (2017b): “Naples, Florida, Remains Top US Metro for

Well-Being“ 4. National Policy

▪ McCarthy (2017a): “US Support for Gay Marriage Edges to New High“

 

▪ Swift (2017b): “More Americans Say Immigrants Help Rather Than Hurt Economy“

▪ Reinhart and Ray (2018): “Record Unhappiness with Women’s Position in U.S.“

5. Higher Education ▪ Auter (2018): “Half of College Students Say Their Major Leads

to a Good Job“ ▪ Maturo (2017): “One in Three Veterans Consult Coworkers

About College Major“ ▪ Auter (2017): “Second Thoughts on College Major Linked to

Source of Advice“

WRITING ASSIGNMENT

e. Go to the Assignment #7, Part 4: Polls forum on the discussion board and make a new post of at least 300 words (in total) in which you provide the following information for each of the three reports you chose to read (three topics x one report per topic). It will be easiest if you write a separate paragraph for each of the three reports.

1. What was the topic of the public opinion poll? 2. Why did you choose this topic (and read this report)? 3. What three findings from this public opinion poll do you think are the most

interesting – and why do you think those three findings are interesting? 4. What was the total sample size? 5. What was the poll’s margin of error? 6. Was the margin of error calculated at the 95% confidence level? 7. What does it mean that the margin of error was calculated at the 95%

confidence level?