✅ Quiz M8.01

✅ Quiz M8.01#

We consider the 2D data as follows:

PCA data cloud

Question

What is the direction of the first component of this data cloud?

  • a) A

  • b) B

  • c) C

  • d) D

Select a single answer

The heatmaps below show the squared loadings of the first three principal components for two different pipelines:

PCA heatmap

Question

Assume the variance of the raw alcohol column is of order 10. What is the difference between pipeline A and pipeline B?

  • a) Pipeline A converted magnesium, alcalinity and malic acid into binary features while Pipeline B retained their original numerical values

  • b) Pipeline B shuffled the data while pipeline A didn’t

  • c) Pipeline B scaled the data while pipeline A didn’t

Select a single answer

Question

In the following cases, select the ones where it is useful to use a PCA:

  • a) To visualize data in the presence of too many features

  • b) To predict consumer churn for internet contracts from the following features: gender, type of internet service provided (Fiber, DSL, etc), payment method, type of day (workday or weekend), state where the person lives

  • c) To predict the pollution in an almost straight river from the GPS coordinates, flow rate and distance to the nearest city

  • d) To reduce underfitting in my supervised task

Select all answers that apply

Questions

Select the true statements about PCA:

  • a) Fewer dimensions means faster training.

  • b) Reducing the number of features with PCA makes a model easier to audit and act on, since fewer dimensions are always simpler to interpret than more.

  • c) By discarding the flat, noisy directions, PCA can reduce overfitting.

Select all answers that apply