SAVVI

Question 1

What are prescriptive analytics?

Answer 1

Analytics that suggests a course of action or strategy based on data, including possible situations or scenarios, available resources, past performance, and current performance.

Question 2

What are descriptive analytics?

Answer 2

Analytics that assess decisions and outcomes after the fact.

Question 3

How is least absolute deviation (l1 regression) a linear programming problem?

Answer 3

Instead of minimizing SUM( | y - a_0 - a_1 x_1 … | ), we create a dummy variable and formulate the + and - sides of the absolute value as constraints: sum(u_i) subject to u_i >= sum_i(y_i - a_0 - a1x1 - …) and u_i >= sum_i(y_i - a_0 - a1x1- …).

Question 4

What is leverage in a linear model?

Answer 4

A measure of the “pull” of individual points on the regression line. Normally given by the corresponding diagonal entry of the hat matrix.

Question 5

Explain cost complexity pruning.

Answer 5

CCP or weakest link pruning calculates a tree score using the sum of squared residuals and an alpha value (tree complexity penalty per leaf). The subtree with the lowest score is accepted.