Module 10 · Project 6 · Due the date on Canvas · PCA & Dimension Reduction · adaptive competency DV18
Rotate the data. Reveal the structure.
Turn a cloud of correlated variables into defensible principal components—without treating PCA as a mysterious R command.
9module steps
4interactive challenges
1PCA evidence defense
60+minutes
Mission progress0%
Begin with the five-minute linear-algebra refresh.
By the end of this module, you will be able to
- Refresh the matrix foundations PCA runs on: standardization and covariance structure.
- Explain why a scaling decision changes the components you get.
- Rotate and interpret components: read loadings and name what each component measures.
- Verify a PCA in browser R and defend which components to keep.
- Audit AI PCA output for invented or uninterpretable structure.
- Apply all of this to Project 6: your DV18 PCA Evidence Studio, due the date on Canvas.
Your evidence map
0 XPDV18
Student learning outcomes
By the end of Module 10, students can…
- Explain component scores as projections — dot products of centered data onto a unit direction.
- Decide when to standardize before PCA and demonstrate the scale effect that raw units create.
- Connect covariance matrices, eigenvectors, and eigenvalues to the maximum-variance direction.
- Interpret loadings, scores, scree plots, and explained variance without causal or construct overreach.
- State what a reduced view omits and defend the retained-component choice in writing.
Module 10 step by step
Each step below is its own short page, so nothing runs on for screens at a time. Work through them in order — your progress is saved as you go, and the numbered bar at the top of every page jumps straight to any step.
- 1RefreshA little linear algebra—only what PCA needs
- 2ScaleExpose the scale effect
- 3RotateFind PC1 by rotating the axis
- 4InterpretRead the loadings without inventing a hidden truth
- 5AI auditAI-output audit
- 6Verify in RVerify the geometry in browser R
- 7DefendDefend a dimension-reduction decision
- 8SubmitSubmit the Module 10 graded assignment
- 9Prove masteryPass the mastery check and record the module