Activity Card for Unit 7

Handout 6

Calculating Conditional Probabilities

In pairs, you will apply your definition of “like” to calculate your conditional probabilities (see example on next page). To do this you will:

• Locate your ratings vector within the whole class ratings matrix and record this vector on a paper.
• Apply your definition of “like” to your own ratings vectors, putting checks and exes next to your ratings vector.
• Add your partners rating vector and preference vector to your paper.
• Conduct the same process that we did when we found the conditional probabilities for Montse and Kristina’s preference (see visual below). That is, find the probability that partner A likes a song given that partner B likes it (i.e. P(A|B)) and then the probability that partner B likes a song given that partner A likes it (i.e. P(B|A)).
• What is the probability that person A likes a song given person A likes a song (i.e. P(A|A)? What is the probability that person B likes a song given person B likes a song (i.e. P(B|B)? Explain.
• What do these probabilities tell you about how ‘similar’ your song preferences are to your partner's song preferences and vice-versa?

Add a picture of your calculations to your unit slide-show. Describe how you can interpret these. (Individual Slideshow Template, Final Project Handout)

Calculating Conditional Probability Resource