week 4 discussion probability
Required Resources
Read/review the following resources for this activity:
 OpenStax Textbook: Chapter 2, 3
 Lesson
 Minimum of 1 scholarly source
In your reference for this assignment, be sure to include both your text/class materials AND your outside reading(s).
Initial Post Instructions
Probability plays a major role in the medical community. Diagnoses are based on probabilities. They are really questions or “what if’s”, and are answered by the probability that the treatment will be the best for the ailment.
Let’s look at probability in terms of both the real world and the medical community.
 Survey 30 people to find out if they are lefthanded or righthanded, and use the following chart to create a contingency table with the information.
Left handed Right handed Total Female Male Total
 Answer the following questions about the information in your contingency table:
 If a person is randomly selected from the survey participants, what is the probability that the person will be lefthanded?
 If you randomly choose a female from the people you surveyed, what is the probability that she is lefthanded?
 What is the odds ratio of choosing a lefthanded female?
 What is the relative risk of choosing a lefthanded female?
Example
Green 
Blue 
Total 

Cats 
40 (A) 
20 (B) 
60 (A+B) 
Dogs 
30 (C) 
40 (D) 
70 (C+D) 
Total 
70 (A+C) 
60 (B+D) 
130 (A+B+C+D) 
 Probability of Green – (A+C)/(A+B+C+D): 70/130 = 54%
 Probability of Green Cat – A/(A+B): 40/60 = 67%
 Odds Ratio of Green Cat – (A/B)/(C/D) or AD/BC: (40*40)/(20*30) = 1600/600 = 2.67%
 Relative Risk of Green Cat – [A/(A+C)]/[B/(B+D)]: (40/70)/(20/60) = 17.14%
 Skim through at least one of the following articles on lefthanded vs. righthanded people from the Chamberlain Library. Answer the following question: How do the probabilities and percentages for your study compare to those in the study you read?