Week 2 — Is This Chart Honest? A Short Data-Display Report

Assignment 2 of the term — read a table and three graphs built from real data, check them for honesty, and explain your choice of chart to someone new to statistics.

This adaptive assignment uses a coaching dialogue to help you turn a first attempt into a clear, evidence-based report. You remain the author. The coach asks questions, checks the reasoning you show, and waits for you to revise before it produces the required report. Last week you sorted variables as categorical or quantitative; this week that sorting decides which table or graph each variable gets. This week's lecture tutorial, quiz, discussion, and Data Lab practise the same ideas from other angles; this assignment is where you put them together on one real decision.

The task

The Palmer penguins field log is a real observational dataset of 344 penguins: 152 Adelie, 68 Chinstrap, and 124 Gentoo, logged on three islands. In the species-by-island table, the Adelie were logged on Biscoe (44), Dream (56), and Torgersen (52); all 68 Chinstrap were on Dream; and all 124 Gentoo were on Biscoe. The 342 penguins with a recorded body mass weigh from 2,700 g to 6,300 g. You will also use the calendar: the 12 months of a common year have 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, and 31 days.

Work these four problems, showing your arithmetic:

1. In the species-by-island table, the Dream column holds 56 Adelie and 68 Chinstrap penguins. How many penguins were logged on Dream?
2. The 342 measured penguin body masses run from 2,700 g to 6,300 g. A histogram uses bins 500 g wide, starting at 2,500 g and ending at 6,500 g. How many bins does it have?
3. The middle value of the 342 penguin body masses is 4,050 g, and their average is 4,201.75 g. By how many grams does the average exceed the middle value?
4. A bar chart of month lengths starts its vertical axis at 26 days. How many times taller does a 31-day month's bar look than February's 28-day bar?

Beside each answer, add one brief interpretation: what that value shows about the table or graph, and one use or limit of it. For problem 3, name the shape of the body-mass distribution by its tail. For problem 4, say how big the real gap between the two months is.

Explain it to a non-expert

The volunteer editor of a community nature-center newsletter has never studied statistics and wants to print one chart of the penguin species counts. Write a 3–5 sentence message that recommends a chart for the species counts, gives a reason tied to these data, and names one limit — for example, that the bars must start at zero so no species looks smaller than it is, or that the field log is an observational study, so the chart describes the penguins but cannot show why the species differ. Explain any technical term in everyday words. More than one recommendation can be defensible.

For a different, ungraded example, imagine a farmers-market manager who wants to show how many shoppers visited on each day of the week. Model answer: "I'd use a simple bar chart with one bar per day, starting the scale at zero. That way a slow day looks only as slow as it really was, and you can compare days at a glance. It shows when people came, but not why, so it can't tell us whether the new music caused a busier Saturday."

Use that pattern for the penguins, with your own recommendation and evidence.

Part 1 — Student instructions

1. Draft all four answers, the four brief interpretations, and your message to the editor before opening a chatbot.
2. Open any course-approved chatbot. Copy the entire Coach Prompt box, including its first and last marker lines, and paste it as one message. The coach will ask for your draft and then work one question at a time.
3. Answer in your own words. Show calculations when asked. Use the coach's feedback to revise at least one calculation or explanation, even if your first attempt was correct.
4. Continue until the prompt's exit condition is met.
5. Save the chat's share link and copy the final report exactly as the coach gives it.

The chatbot is a coach, not a ghostwriter. It must draw out your reasoning rather than write the report for you.

Coach Prompt

COPY EVERYTHING BELOW THIS LINE
ROLE: You are a careful learning coach. Draw out and challenge MY thinking about tables, graphs, and the shape of data. Do not write my assignment for me and do not invent work I did not show.

ASSIGNMENT: Work through these four problems in order, one at a time. Do not invent, replace, or reorder a problem. The data: the Palmer penguins field log, an observational dataset of 344 penguins (152 Adelie, 68 Chinstrap, 124 Gentoo); Adelie on Biscoe (44), Dream (56), and Torgersen (52), all 68 Chinstrap on Dream, all 124 Gentoo on Biscoe; 342 recorded body masses from 2,700 g to 6,300 g. The calendar: the 12 month lengths of a common year are 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 days.
PROBLEM P1: In the species-by-island table, the Dream column holds 56 Adelie and 68 Chinstrap penguins. How many penguins were logged on Dream?
PROBLEM P2: The 342 measured penguin body masses run from 2,700 g to 6,300 g. A histogram uses bins 500 g wide, starting at 2,500 g and ending at 6,500 g. How many bins does it have?
PROBLEM P3: The middle value of the 342 penguin body masses is 4,050 g, and their average is 4,201.75 g. By how many grams does the average exceed the middle value?
PROBLEM P4: A bar chart of month lengths starts its vertical axis at 26 days. How many times taller does a 31-day month's bar look than February's 28-day bar?
After the four answers, I must briefly interpret each one: what that value shows about the table or graph and one use or limit of it; for P3, the shape of the body-mass distribution named by its tail; for P4, how big the real gap between the two months is. I must then write a 3-5 sentence message to a newsletter editor who is new to statistics, recommending a chart for the species counts with a reason tied to these data and naming one limit. I must explain technical terms in everyday words.

SCORING CRITERIA: Score only evidence I supply: correct table and graph computations (40 points), graph choice and shape reasoning (32 points), clarity for a non-expert reader (16 points), and showing work so it can be checked (12 points). For each of P1-P4, give 2, 1, or 0 evidence units per criterion; one unit is worth 5 computation points, 4 reasoning points, 2 clarity points, or 1.5 showing-work points. Sum all four problems within each criterion. Count my final message only with P4, not again with P1-P3.
COMPUTATION UNITS: A correct total, bin count, difference, or ratio = 2; the right values and operation with only an arithmetic slip = 1; a missing result or the wrong values or operation = 0. Do not penalize an alternative valid method or equivalent correct notation.
REASONING UNITS: For P1-P3 separately, an accurate account of what that value shows about the display plus a use or limit tied to the penguin or calendar data = 2; exactly one of the two = 1; neither = 0. For P3, a skew named by where the pile sits instead of by its tail does not count. For P4, BOTH an accurate explanation of how the axis start exaggerates a 3-day gap AND a final recommendation with a data-specific reason and a named limit = 2. If full P4 evidence is absent but at least one accurate substantive part appears, give 1. No accurate reasoning = 0; naming a chart alone does not earn a unit. An arithmetic slip alone is not a reasoning error.
CLARITY UNITS: For each problem, labeled evidence understandable to someone new to statistics, with technical terms explained = 2; intelligible evidence that needs rereading because of ambiguity or jargon = 1; absent or unintelligible evidence = 0. Include the final message with P4 if submitted. Missing reasoning alone does not lower clarity for otherwise clear submitted work.
SHOWING-WORK UNITS: For each problem, checkable values and steps = 2; a relevant but incomplete value or step = 1; a result alone or no method = 0. A visible method stays checkable despite an arithmetic slip.

Do NOT invent grading rules.

DIALOGUE RULES: Ask exactly one question per message and wait for my answer. Start by asking for my complete first attempt. Build each next question from my exact words. Probe an unsupported claim and ask me to examine its evidence. Keep the conversation focused on questions rather than completed work.

ENGAGEMENT GUARDS: A greeting, copied prompt, yes/no reply, or one-word answer is not a substantive exchange. Do not flatter or accept agreement as evidence. Praise only a concrete move I made. If evidence is missing, say what is missing and ask for it. Require a real revision plus a short reflection on why the revision is better. Do not issue the report early.

EXIT CONDITION: Continue until at least five substantive exchanges have occurred AND I have supplied all four answers and their brief interpretations AND written my recommendation to the editor AND revised at least one calculation or explanation AND reflected on the revision. Stop only after whichever requirement happens last.

REPORT: After the exit condition is satisfied, output exactly these labelled lines in this order. Replace X with the exact earned score; it may end in .5 and must not be rounded to a whole number. Base every line only on evidence in this chat; write "Not supplied" for missing evidence and never raise the score for polished chatbot prose.
STUDENT'S SCORE: X/100
EVIDENCE FOR THE SCORE: [specific evidence from my calculations and reasoning]
REVISION MADE: [what I changed and why]
STRENGTH: [one earned strength]
NEXT STEP: [one concrete improvement]
Then tell me to submit this report, my revised data-display report, and the share link.
COPY EVERYTHING ABOVE THIS LINE

Deliverables

Submit these three items in the assignment entry:

• your revised data-display report with all four answers, their brief interpretations, and your message to the editor — written, or recorded as audio or video with a transcript, or as a labelled sketch of the charts with a short note; every form is graded by the same scoring criteria;
• the coach's five-line report; and
• the conversation share link.

Submit in any accessible file type or as a link; a recorded response may be submitted as audio or video with a transcript, or as text.

Equivalent route (no AI required)

This route assesses the same Week 2 skills — reading a two-way table, choosing and setting up a graph for a quantitative variable, naming a distribution's shape by its tail, and catching a misleading graph — for comparable time and effort, about 60 to 90 minutes, the same as the coached route. Complete the same four problems, the four brief interpretations, and the message to the editor. Then audit your own first draft against the attached scoring criteria, criterion by criterion, and write a second draft. Add a 150–200 word revision memo that names one calculation or explanation you changed, the evidence that prompted the change, and one question you still have. Submit the revised data-display report, your completed criteria checklist, and the revision memo in the assignment entry; together they replace the share link and the coach's report. This route uses the same scoring criteria and the same points, with no penalty for choosing it.

How you'll be graded

The full analytic rubric is attached to this assignment in Canvas.

Academic integrity and AI use

The calculations, reasoning, revision, and final report must be your own. Do not ask the chatbot to create the assignment or add evidence you did not produce. Submit an honest share link from your own dialogue. The equivalent route keeps the same workload and evidence and requires no AI account.

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