Lifestyle Management
through System Analysis
 

Measuring Impact of a Cause:  Conditional Probability

Conditional probabilities are used to measure the impact of a cause on your behavior.  This lecture introduces you to the calculation of conditional probability.

Objectives

1. Define probability
2. Test for conditional independence among various causes of your behavior
3. Make a causal model of what leads to your behavior
4. Measure the impact of a cause on your behavior using probability statements

Assigned Reading

1. Read introduction to probability concepts  More►

Presentations

1. Lecture on measuring impact of a cause:
   • Part one: Lecture  Slides► Slides 2003►  Listen►  SWF►  IPOD►
   • Part two:  Examples  Listen►  SWF►  IPOD►

 

What you know?

Advanced learners like you, often need different ways of understanding a topic. Reading is just one way of understanding. Another way is through writing about what you have read.  The enclosed assessment is designed to get you to think more about the concepts taught in this session. 

1. What is the definition of probability?
2. What is definition of conditional probability?
3. How is the impact of a cause on the effect measured?
4. What is meant by shrinking universe and how is this concept useful in calculation of probabilities?

Assignment Due this Week

1. Every week ask a question or comment on the lecture.  Comment►  Ask►

2. Calculate the probability of sleeping early, probability of exercising and conditional probability of exercise after sleeping late from the following Table:
   

   	Morning exercise	No morning exercise	Total
   Sleep early	0.60	0.20
   Sleep late	0.05	0.15
   Total
   Table5:   Joint probability of exercise and sleeping early

3. A person has hypothesized that there are two causes of his exercise:  sleeping early and having an appointment with a buddy to exercise with,  He has collected two weeks of data presented in Table 6.  Calculate which cause is more likely to lead to exercise.  See it done►   SWF►
   

   Day	Sleeping early	Planning with buddy	Exercise
   1	Yes	No	No
   2	Yes	No	No
   3	Yes	No	No
   4	No	No	No
   5	No	No	No
   6	No	No	No
   7	No	No	No
   8	Yes	Yes	Yes
   9	Yes	Yes	Yes
   10	Yes	Yes	Yes
   11	Yes	Yes	Yes
   12	Yes	No	Yes
   13	No	Yes	Yes
   14	No	Yes	Yes
   15	No	Yes	Yes
   12	No	Yes	Yes
   Table 6: A Causal Diary of Exercise