AP Statistics - Unit 1 - Topic 1.1
Introducing Statistics What Can We Learn from Data?
Statistics begins with a question. A good question leads us to collect useful data, notice patterns, and make careful conclusions instead of just guessing.
Start Here
Use these boxes as your quick lesson notes before practicing.
Definition: Statistics
Statistics is the study of collecting, organizing, analyzing, and using data to answer questions.
Important Idea
A question is statistical when the answer can vary. Different people or situations can give different data values.
Formula: Percent
Percent = part / whole x 100
Simple Example
Statistical: How many hours of sleep do students get on school nights? The answers will not all be the same.
How To Spot A Statistical Question
Ask these three questions. If all three answers are yes, you probably have a good statistical question.
The 3-Part Check
Example: students in this class, families in a city, players on a team.
A variable is what you measure or record, like height, time, opinion, or score.
If the answers can be different, statistics can help us learn from the data.
AP Exam Skill Builder
This is the extra layer that helps students answer AP-style prompts with confidence.
What Makes An Investigative Question Valid?
A valid investigative question is not just interesting. It must be possible to answer with data.
What Information Should You Identify?
When AP Statistics asks what information is needed, look for these parts.
Worked Examples
Read each example like a mini AP free-response check.
How many minutes do students at Lincoln High spend on homework on a typical school night?
Why it works: It has a clear group, a measurable variable, and answers will vary.
Do students like school?
Problem: This is too vague. "Like" could mean classes, teachers, lunch, clubs, or friends.
Better question: What percent of students at our school say their classes are interesting?
What is the temperature in the classroom right now?
Why not: This asks for one fixed value at one moment. It does not study variability across individuals or situations.
Make it statistical: How does the classroom temperature change during the school day?
Does more study time usually go with higher quiz scores?
Information needed: For each student, collect study time and quiz score. You need both variables from the same individuals.
Why is online homework better than paper homework?
Problem: This is leading because it already suggests online homework is better.
Better question: Which type of homework do students prefer: online homework or paper homework?
Common AP Mistakes
These are small wording mistakes that can cost points.
Mistake 1: No Group
Weak: How much sleep do people get?
Better: How much sleep do students in this AP Statistics class get on school nights?
Mistake 2: No Variability
Weak: How old am I?
Better: How old are students in this class?
Mistake 3: Too Vague
Weak: Are students healthy?
Better: How many days per week do students exercise for at least 30 minutes?
Mistake 4: Leading Wording
Weak: Why is our cafeteria food bad?
Better: How do students rate the cafeteria food on a scale from 1 to 5?
Key Vocabulary
These are the words AP Statistics expects you to use clearly.
Data
Information collected to answer a question.
Individual
One person, object, or case we collect data from.
Variable
A characteristic recorded for each individual.
Population
The entire group we want to learn about.
Sample
A smaller part of the population that we actually collect data from.
Variability
Differences in data values. Statistics is useful because values often vary.
Flashcard Practice
Work through the deck. Mark cards you know, and send tricky cards back to practice again.
Multiple-Choice Practice
Answer one question at a time. You will get instant feedback and a review at the end.
FRQ-Style Practice
Prompt: A class collects data related to statistical questions and data variation. Write a free-response answer that uses the correct vocabulary and statistical reasoning.
- Identify the variable(s), population/sample, or study design feature requested.
- Choose or describe the appropriate table, graph, summary statistic, sampling method, or design decision.
- Write one contextual interpretation that uses statistical language rather than a vague everyday claim.
Scoring focus: Credit depends on precise vocabulary, context, and a justified choice or description.
Calculator and Technology Check
Output to read: Calculator or spreadsheet output gives n = 48, mean = 16.2, median = 15.4, IQR = 4.8, and one flagged high value.
How to interpret it: For statistical questions and data variation, connect the output to the context: compare resistant and nonresistant summaries, mention units, and decide whether the flagged value changes the story.
Source note: Aligned to AP Statistics Course and Exam Description, Effective Fall 2026.