Föreläsning 4 (classification)

Question 1

Why is classification different from regression?

Answer 1

We have a finite number of
labels. Unlike numbers the labels
are not ordered.

Question 2

What are some practical applications of classification? (Name at least 5 of the examples from slides)

Answer 2

• Will this treatment help that person?
• Will this person pay back that loan?
• Will this person like that book?
• Is this email spam or not?
• Is this review positive or negative or neutral?
• What musical genre does this song belong to?
• What breed of dog does this picture show?

Question 3

What is a good classifier?

Answer 3

One that performs well on previously unseen parts of the data set

Question 4

Why do we use a confusion matrix?

Answer 4

For understanding the strengths and weaknesses of a classifier

Question 5

What is the K-NN algorithm?

Answer 5

K-NN means K-nearest neighbours and is a classification algorithm that chooses the nearest neighbours to a data point. Nearest in this case means distancewise

Question 6

Is it appropriate to use decision trees for classification?

Answer 6

yes woho very appropriate

Question 7

What is the formula to calculate gini impurity?

Answer 7

Gini = 1 – p(+)^2 – p(-)^2