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If your course hands out .twbx workbooks or CSV files and you're on a Mac, a Chromebook or a shared lab PC, use xmetric: it's free, runs in the browser with no install or student-ID check, and keeps your files private. Use Tableau Public if you're graded on a public portfolio link, and Power BI Desktop if the course grades DAX on Windows.
Our pick
xmetric
Free with no verification wait, runs on any laptop with a browser, opens the course's .twbx files with their formulas, and teaches the same shelves, LOD expressions and table calculations the course uses.
Pick something else if
The assignment is a public Tableau Public link (Tableau Public), the course grades DAX and Power Query in .pbix files on Windows (Power BI Desktop), or you want Tableau's full desktop app on your own Mac or PC (Tableau Desktop Free Edition).
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Here are final exam scores for 1,200 first-year students. Tutored students average 67.6, untutored 71.5: tutoring looks like it hurts. Split by course and it flips. In all four courses, tutored students score 5.8 to 6.6 points higher. The overall number reversed because 63% of Calculus I students use tutoring and only 8% of Academic Writing students do. That's Simpson's paradox, and three views show it.
Computed by the xmetric engine
The data
1,200 first-year students across four courses, from Calculus I to Academic Writing. Each row is one student's final exam score, their weekly study hours, and whether they used the tutoring centre.
student_id | course | tutoring | study_hours_per_week | exam_score |
|---|---|---|---|---|
| S0329 | Intro to Statistics | Not tutored | 7.8 | 63 |
| S1189 | Academic Writing | Not tutored | 6.9 | 94 |
| S1146 | Academic Writing | Not tutored | 7.5 | 94 |
| S0625 | Microeconomics | Tutored | 6.5 | 84 |
Step 1
Tutored students score lower. Read on before you write that tutoring doesn't work.
Tableau
AVG([exam_score])
// tutoring on ColumnsSQL
SELECT
tutoring,
COUNT(*) AS students,
ROUND(AVG(exam_score), 1) AS avg_score
FROM input
GROUP BY tutoring
ORDER BY tutoringRows
| Tutoring | Students | Avg score |
|---|---|---|
| Not tutored | 796 | 71.5 |
| Tutored | 404 | 67.6 |
Step 2
In every single course, tutored students score higher. The overall average reversed because hard courses send far more students to tutoring: most of Calculus I goes, almost none of Academic Writing.
Tableau
AVG([exam_score])
// course on Columns, tutoring on ColorSQL
SELECT
course,
tutoring,
COUNT(*) AS students,
ROUND(AVG(exam_score), 1) AS avg_score
FROM input
GROUP BY course, tutoring
ORDER BY course, tutoringRows
| Course | Tutoring | Students | Avg score |
|---|---|---|---|
| Academic Writing | Not tutored | 276 | 81.2 |
| Academic Writing | Tutored | 24 | 87 |
| Calculus I | Not tutored | 110 | 53.3 |
| Calculus I | Tutored | 190 | 59.9 |
| Intro to Statistics | Not tutored | 161 | 64.3 |
| Intro to Statistics | Tutored | 139 | 70.3 |
| Microeconomics | Not tutored | 249 | 73.3 |
| Microeconomics | Tutored | 51 | 79.5 |
Step 3
The FIXED expression gives every row its course's average, whatever is on the view. Measured against their own course, tutored students are above average and the rest below.
Tableau
AVG([exam_score] - { FIXED [course] : AVG([exam_score]) })SQL
WITH t AS (
SELECT
tutoring,
exam_score
- AVG(exam_score) OVER (PARTITION BY course) AS vs_course_avg
FROM input
)
SELECT
tutoring,
ROUND(AVG(vs_course_avg), 1) AS points_vs_course_avg
FROM t
GROUP BY tutoring
ORDER BY tutoringRows
| Tutoring | Points vs course avg |
|---|---|
| Not tutored | −1.6 |
| Tutored | 3.2 |
The last step is the one to learn: a FIXED expression that gives every row its group's average, so you compare each student with their own course. Against that baseline, tutored students sit 3.2 points above and the rest 1.6 below.
Common mistake
Tutored students are mostly in the hardest courses, so the overall average compares Calculus I with Academic Writing, not tutored with untutored. Compare within each course, or against the course average.
Tableau
AVG([exam_score])
// tutoring onlySQL
SELECT tutoring, ROUND(AVG(exam_score), 1) AS avg_score
FROM input
GROUP BY tutoring
ORDER BY tutoringTableau
AVG([exam_score] - { FIXED [course] : AVG([exam_score]) })SQL
WITH t AS (
SELECT
tutoring,
exam_score
- AVG(exam_score) OVER (PARTITION BY course) AS vs_course_avg
FROM input
)
SELECT
tutoring,
ROUND(AVG(vs_course_avg), 1) AS points_vs_course_avg
FROM t
GROUP BY tutoring
ORDER BY tutoringDrop the CSV from your course here and the same steps run on it, in your browser. For a .twbx, open it in the xmetric app. Nothing is uploaded.
Drop a CSV anywhere on this page
Up to 10,000 rows. The sample, exam_results.csv, shows the shape.
If this is you
A Mac, Chromebook or lab PC and a .twbx or CSV from the course
xmetric
Nothing to install, no ID check, files stay private.
If this is you
You're graded on a public portfolio link, or building one for recruiters
Tableau Public
Free, and the profile is made to be seen. Workbooks and data published to a Tableau Public profile are not private: anyone can interact with the views or download the workbooks and data sources.
If this is you
The course grades DAX measures and Power Query in .pbix files
Power BI Desktop
Free to install. Sharing reports needs Pro or Premium; Desktop is Windows-only; the service needs a work or school email.
If this is you
You want the full Tableau desktop app on your own laptop
Tableau
Tableau Desktop Free Edition: full Desktop analytics for one person, stored locally; no publishing, online sharing or sharing packaged workbooks.
No. Open it in your browser and drop your file. You only sign in if you want to save a workbook online.
Yes. Open it in the xmetric app to build new views, or drop it into the workbook inspector to list its sheets and read every calculated field the instructor wrote.
Yes. xmetric runs in the browser, so anything that runs Chrome runs it.
Files you open stay in your browser and are not uploaded unless you save the workbook online. For Tableau Public: Workbooks and data published to a Tableau Public profile are not private: anyone can interact with the views or download the workbooks and data sources.
A trend that shows up in every group and reverses when you combine the groups. It happens when the groups differ in size and in their baseline, like tutoring use and course difficulty in the demo.