Practical statistics, from data to decisions

Six modules that build on each other: describe a data set, picture it, reason about chance, sample, estimate, then relate two variables. You finish with a capstone on a question you care about.

Beginner
6 weeks
Online, recorded
Sheets or Excel

Choose a plan Read lesson 1.4 free

What you'll learn, week by week

34 lessons of 12 to 20 minutes. Lesson 1.4 is open to everyone; the rest open the day you enroll.

Week1

Describing data

7 lessons1 h 41 minQuiz: 10 questions

Not started1.1Types of data Reading12 min
Not started1.2The center: mean, median, mode Reading14 min
Not started1.3Shape and skew Video15 min
Not started1.4Measuring spreadFree preview18 min
Not started1.5Percentiles and box plots Reading16 min
Not started1.6Outliers, and what to do with them Video14 min
Not started1.7Describe a data set in one paragraph Practice12 min

Week2

Picturing distributions

6 lessons1 h 28 minQuiz: 10 questions

Not started2.1Histograms that tell the truth Reading15 min
Not started2.2Choosing a bin width Practice12 min
Not started2.3Reading a box plot Reading14 min
Not started2.4Comparing two groups on one chart Video16 min
Not started2.5Scatter plots before correlation Reading15 min
Not started2.6Five charts that mislead Practice16 min

Week3

Probability you'll actually use

6 lessons1 h 35 minQuiz: 10 questions

Not started3.1Counting outcomes without a formula14 min
Not started3.2Base rates and the screening test18 min
Not started3.3Conditional probability with a table17 min
Not started3.4Expected value at the grocery store15 min

Week4

Sampling and the normal curve

5 lessons1 h 22 minQuiz: 10 questions

Not started4.1Why samples vary16 min
Not started4.2z-scores and the normal curve17 min
Not started4.3The standard error, not the standard deviation18 min

Week5

Estimating and testing

5 lessons1 h 18 minQuiz: 10 questions

Not started5.1Confidence intervals in plain words18 min
Not started5.2What a p-value is not16 min
Not started5.3Two kinds of being wrong15 min

Week6

Relationships and your capstone

5 lessons1 h 10 min, plus the capstone

Not started6.1Correlation without the mystery15 min
Not started6.2Fitting a straight line17 min
Not started6.5Capstone: one question, your dataSelf-paced

The January cohort, by the week

Every week has the same rhythm: lessons whenever suits you, a live session on Tuesday, office hours on Thursday and a quiz due on Sunday.

Can't make Tuesdays?Every session is recorded and posted within two hours. Office hours questions can be sent ahead.

Week 1 Jan 11 to 15, 2027

Tue12Kickoff and live session: describing data6:00 pm Eastern · 75 minFirst
Thu14Office hours with Lena12:30 pm Eastern · 45 minOffice hours
Sun17Module 1 quiz due11:59 pm Eastern · retake onceDue

Week 2 Jan 18 to 22, 2027

Tue19Live session: picturing distributions6:00 pm Eastern · 60 minLive
Thu21Office hours with Tomás12:30 pm Eastern · 45 minOffice hours
Sun24Module 2 quiz due11:59 pm EasternDue

Weeks 3 to 6 follow the same pattern and end with the capstone, due Friday, February 19.

Who teaches it

Two instructors write and teach the course. A cohort lead keeps the discussion space moving and answers anything about logistics.

Lena Marsh
Founder and lead instructor

Eleven years as a survey statistician for a county health department, explaining confidence intervals to people with a budget meeting in an hour.
- Writes and teaches Modules 1 to 3
- Office hours odd weeks, Thursdays 12:30 pm Eastern
Tomás Reyes
Instructor

Taught introductory statistics at a community college for nine years and still reads every capstone himself.
- Writes and teaches Modules 4 to 6
- Office hours even weeks, Thursdays 12:30 pm Eastern
Amara Osei
Cohort lead and learner support

Runs the cohort space, schedules, refunds and certificates. If a question isn't about statistics, it reaches Amara first.
- Answers within one working day
- Reachable from the contact page

Pick how you'll take it

The lessons are identical in every plan. Compare the details on the pricing page.

Self-paced

All 34 lessons and quizzes, open for a year.

$149one payment

Every lesson, quiz and worksheet
Certificate of completion
No live sessions or capstone feedback

Start self-paced todayStarts the day you enroll

With live sessions

Cohort

Six weeks with a group, a schedule and people to ask.

$349one payment

Everything in self-paced
Six live sessions and six office hours
Written feedback on your capstone

Enroll for January 11Enrollment closes January 4

Team

Five cohort seats for a team that learns together.

$1,190five seats, $238 each

Cohort access for five people
Kickoff call and a progress report
Invoice and purchase-order billing

Ask about team seatsAdd seats at $238 each

Not for you after the first week? Email us within 14 days for a full refund. No form, no questions.

About the course

What do I need to know before week 1?

How to add, divide and use a spreadsheet formula like SUM. Lesson 1.1 starts from "what kind of data is this?" and builds from there.

What is the capstone?

A two-page analysis that answers one question with data you choose: from work, a hobby or one of the course's public data sets. Cohort learners get written feedback within a week.

Is there a certificate?

Yes. Pass all six module quizzes with 7 out of 10 or better and you get a certificate with a verification link. Cohort certificates also list the capstone. See a sample.

Can I switch from self-paced to a cohort?

Any time before a cohort starts. You pay the $200 difference and keep your progress.

Not sure yet? Read lesson 1.4.

It's the full lesson, with the worked example, three practice questions and the flashcards. No account needed.

Open the free lesson

About 18 minutes.