Unit 7: How to Evaluate Descriptive and Inferential Statistics

Unit 7: Assignment #1 (due before 11:59 pm Central on Wednesday September 29):

  1. To review what descriptive and inferential statistics are, why they are important to learn, and examples of how they are used:
    1. Watch Lynda.com’s (2010) video, “Understanding Descriptive and Inferential Statistics.”
    2. Read Laerd Statistics’ (no date) article, “Descriptive and Inferential Statistics” (web link).
    3. Read a section of Wikipedia’s (2020) entry, “Descriptive Statistics” (web link).
    4. Read Statistics HowTo’s (2014) article, “Inferential Statistics: Definition, Uses” (web link).
  2. 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 watching the latter part of Professor Gernsbacher’s lecture video, “The Five-Paragraph Model” (a transcript of the video is available in PDF and Word).
  3. Write one five-paragraph Examples-Style essay (using examples to support) the thesis that “Descriptive statistics are useful.” Remember that descriptive statistics can be graphs and figures, as well as means and modes. And remember to use examples of descriptive statistics, not reasons to use descriptive statistics.
    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 is ONE sentence that captures all three  of your three examples.
    3. Check your essay to make sure it has three Examples Paragraphs.
    4. Check your essay to make sure it has a Conclusion Paragraph.
    5. Check your Conclusion Paragraph to make sure it has a Re-stated Thesis Statement and ends with something (mildly) witty or profound.
    6. Check your Re-stated Thesis Statement to make sure that it is ONE sentence that summarizes all three of your three examples.
    7. Check ALL FIVE of your paragraphs — your Introduction Paragraph, each of your three Examples Paragraphs, and your Conclusion Paragraph — to make sure each of your five paragraphs has FIVE sentences (a Topic Sentence, three Supporting Sentences, and a Conclusion Sentence).
    8. Save your essay as a PDF and name the file YourLastname_DescriptiveEssay.pdf.
  4. Write another five-paragraph Examples-Style essay (using examples to support), this time to support the thesis “Inferential statistics are useful.” Remember to use examples of inferential statistics, not reasons to use inferential statistics.
    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 is ONE sentence that incorporates all three of your three examples.
    3. Check your essay to make sure it has three Examples Paragraphs.
    4. Check your essay to make sure it has a Conclusion Paragraph.
    5. Check your Conclusion Paragraph to make sure it has a Re-stated Thesis Statement and ends with something (mildly) witty or profound
    6. Check your Re-stated Thesis Statement to make sure that it is ONE sentence that summarizes all three of your three examples.
    7. Check ALL FIVE of your paragraphs — your Introduction Paragraph, each of your three Examples Paragraphs, and your Conclusion Paragraph — to make sure each of your five paragraphs has FIVE sentences (a Topic Sentence, three Supporting Sentences, and a Conclusion Sentence).
    8. Save your second essay as a PDF and name the file YourLastname_InferentialEssay.pdf.
  5. 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 (Word), who is widely considered the father of U.S. Psychology!
  6. Go to the Unit 7: Assignment #1 Discussion Board and make a new Discussion Board post.
    1. First, attach your Descriptive Statistics Essay, saved as a PDF.
    2. Remember to “Attach” your Descriptive Statistics Essay PDF and not use the “File” tool.
    3. Because the Discussion Board will allow only one file to be attached to each post, make a reply post to your own post.
    4. Use your reply post to attach your Inferential Statistics Essay, saved as a PDF.
    5. You should write both essays, and then make your Discussion Board post, because if you turn in only one essay (or turn in one essay a while before you turn in the other), only one essay is what we’ll be alerted to grade.

Unit 7: Assignment #2 (due before 11:59 pm Central on Thursday September 30):

  1. 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 (Text-Only Word version) 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.
    5. Chapters 5 and 6 explain deception by graphs and figures.
  2. 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.
  3. 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 PPT; (2) an Infographic; 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.
  4. Go to the Unit 7: Assignment #2 Discussion Board and
    1. attach your teaching document PDF, and
    2. tell us the intended audience of your teaching document and why you chose that intended audience.

Unit 7: Assignment #3 (due before 11:59 pm Central on Friday October 1):

  1. 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” (web link).
    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.
  2. 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” (web link).
    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.
  3. Now it’s time to apply Chapman and Louis’s (2017) “Seven Sins of Statistical Misinterpretation” (web link) to scientific articles you have read.
    1. Choose three of the 9 articles that you found and read in Unit #5 and that you synthesized in Unit #6.
    2. Choose the three articles (of your 9 articles) that will be the easiest (and most logical) to evaluate according to Chapman and Louis’s (2017) “Seven Sins of Statistical Misinterpretation” (web link).
    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_PSY-311_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. Make sure that your citation in the citation text box at the top of the page is in APA style (see Unit 5). It’s okay, for this assignment, if you can’t italicize parts of the citation (in the citation text box of the fillable PDF).
  4. Go the Unit 7: Assignment #3 Discussion Board and attach your filled in PDF.

Unit 7: Assignment #4 (due before 11:59 pm Central on Sunday October 3):

  1. To answer some of the questions you might have about public opinion polls and surveys, read Langers’ (2008) article, “ABC News’ Guide to Polls & Public Opinion” (web link).
    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.”
  2. 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” (web link).
    2. Make sure you understand the difference between sampling a population and surveying (or polling) an entire population.
    3. Make sure you understand what a margin of error means in a public opinion poll or survey.
  3. 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” (web link).
    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.
  4. 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
    2. Finance
    3. Well-Being
    4. National Policy
    5. Higher Education
  5. Go to the Unit 7: Assignment #4 and #5 Discussion Board and make a new post of at least 300 words in which you provide the following information for each of the three reports you chose to read (three topics × 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?

Unit 7: Assignment #5 (due before 11:59 pm Central on Monday October 4):

  1. Go to the Unit 7: Assignment #4 and #5 Discussion Board and read all the other students’ posts.
  2. Reply to three other students; each of your three responses should be at least 200 words.
    1. One of your responses must be to a student who wrote about at least one of the topics that you also wrote about.
    2. One of your responses must be to a student who wrote about at least one topics that you did NOT write about.
    3. Your third response can be to any other student (besides the two students you responded to in 1. and 2. above).
    4. If no other student wrote about one of the topics that you also wrote about, you can respond to three students who all wrote about different topics than you wrote about.

Unit 7: Assignment #6 (due before 11:59 pm Central on Tuesday October 5):

  1. Read both essays that each of the other members of your small Chat Group posted on the Unit 7: Assignment #1 Discussion Board. If you are in a Chat Group with two other students, that means you will read four essays; if you are in a Chat Group with only one other student, that means you will read two essays.
  2. Review how to provide peer review on your Chat Group members’ essays by reading the Peer Review Guidelines (Word). Note that you will again be answering 12 questions about each member’s essays.
  3. Meet online with your small Chat Group at the time your Chat Group arranged for a one-hour text-based Chat.
    1. Prior to your Chat Group meeting online, all members of your Chat Group must have completed steps a. and b. of this Assignment.
    2. Then, spend the remainder of your hour-long Chat with each Chat Group member providing peer review of the other Chat Group members’ essays.
  4. At the end of your one-hour Chat:
    1. Nominate one member of your Chat Group (who participated in the Chat) to make a post on the Unit 7: Assignment #6 Discussion Board that summarizes your Group Chat in at least 200 words.
    2. Nominate another member of your Chat Group (who also participated in the Chat) to save the Chat transcript as a PDF, as described in the Course How To (under the topic, “How to Save and Attach a Group Text Chat Transcript”), and attach the Chat transcript to a post on the Unit 7: Assignment #6 Discussion Board.
    3. Nominate another member of your Chat Group (who also participated in the Chat) to make another post on the Unit 7: Assignment #6 Discussion Board that states the name of your Chat Group, the names of the Chat Group members who participated the Chat, the date of your Chat, and the start and stop time of your Chat.
    4. If only two persons participated in the Chat, then one of those two persons needs to do two of the above three tasks.
    5. Before ending the Group Chat, bid goodbye to each other. In the next Unit you will be forming new Chat Groups!
  5. All members of the Chat Group must record a typical Unit entry in your own Course Journal for Unit 7.

Congratulations, you have finished Unit 7! Onward to Unit 8!

 

Open-Access Active-Learning Research Methods Course by Morton Ann Gernsbacher, PhD is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. The materials have been modified to add various ADA-compliant accessibility features, in some cases including alternative text-only versions.
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