Lecture 13 - Presentation and Speed

Question 1

What is lie factor?

Answer 1

Ratio of size of effect shown in the graph to size of effect in data

Question 2

What is data density?

Answer 2

Ratio of number or entries in data matrix to area of data graphic

Question 3

What are the two goals when presenting data?

Answer 3

convey story

establish credibility

Question 4

What steps should you take when producing a plot?

Answer 4

Plot the graph
Highlight residuals
Refine the fit
Fake CI about the predictions
Add a legend
Mathematics specifying the model
Add parameter estimates

Question 5

What are two reasons why R is slow?

Answer 5

The language itself - decisions made when it was invented
The way the language is implemented - changes to base R made by members of core R team, only 6 active members, overriding concern is to make R stable rather than fast.

Question 6

What is a profiler?

Answer 6

Piece of software that records instructions computer is executing

Question 7

Why do profilers slow code?

Answer 7

Observer effect - act of observation influences the phenomenon being observed

Question 8

What does profvis do?

Answer 8

Provides visual depiction of slow portions of the code