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Recommender systems Nicole and Kirstin

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Page 1: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Recommender systems

Nicole and Kirstin

Page 2: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

What is a recommender system?

• A system tries to predict if a user will like an item.

• The system recommends to a user items that it thinks the user will like.

Page 3: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

What would you want recommendations for?

Page 4: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

How do you make recommendations?

• Your friend is looking for a new book to read.

• How can a system make recommendations?

Page 5: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Two types of information can inform recommendations.

Similar people have similar tastes.

People like related items.

We liked Harry Potter—you’ll love it!

I like historical fiction!

I like fantasy!

Page 6: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Similar people have similar tastes!

Peggy

Christine

Collaborative Filtering (CF)

Page 7: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

People like related items!

Susan

Molly

Content-based filtering (CB)

Page 8: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Let’s do an example together

Peggy

Christine

Brandon

Page 9: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Peggy

Christine

Brandon

Ricky

Collaborative filtering looks at similar users

Page 10: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Peggy

Christine

Brandon

Ricky

Content-based looks at the items themselves

Cartoons

Page 11: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Which do you think works better?

Collaborative filtering: Similar people have similar tastes.

Content-based filtering: People like related items.

We liked Harry Potter—you’ll love it!

I like historical fiction!

I like fantasy!

Page 12: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Should you recommend this?

Christine

Ricky

Sashank

Page 13: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Should you recommend this?

Maria

Sue

Caitlin

Page 14: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

What should you recommend?

Nancy

Hannah

Priya

Page 15: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Should you recommend this?

Nancy

Hannah

Priya

Page 16: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

How are these items and people related?

Michelle

Katy

Jan

Alice

Anjali

Page 17: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Michelle

Katy

Jan

Alice

Anjali

Page 18: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Alex

Simone

Gina

Page 19: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Training Set

Sashank

Brandon

Maria

Christine

Susan

Jesse

Page 20: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Test Case 1: Michelle

Michelle

Page 21: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Test Case 2: Katy

Katy

Page 22: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Test Case 3: Jan

Jan

Page 23: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

How can you improve these systems?

• What were some downfalls of each method?

– Collaborative filtering

• Hard to answer when new person hasn’t seen/read/bought anything that other people have

– Content-based filtering

• Hard to answer when someone doesn’t have a clear profile of interests

• Hybrid approaches combine elements of both collaborative and content-based filtering.

Page 24: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Netflix is mainly content-based

Page 25: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Netflix attempted to get better algorithms…

But the winner turned out to be too complicated to practically use!

Page 26: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Pandora is also content-based

“The Music Genome Project”

Page 27: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Amazon uses both

Page 28: Recommender systems Nicole and Kirstin - Women@SCSRecommender systems Nicole and Kirstin . What is a recommender system? •A system tries to predict if a user will like an item. •The

Where else could recommender systems be helpful?