George Mason University

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.


  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►


  1. Lecture on measuring impact of a cause:


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


    Sleep early




    Sleep late




    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


  •  Use of conditional probability in measuring impact of causes PubMed►
  • Analytical prevention of relapse  PubMed►

This page is part of the course on Lifestyle Management   This page was last edited on 10/22/11 by Farrokh Alemi, Ph.D ©Copyright protected.