# Chamberlain Odds Ratio of Choosing Left Handed Female Probability Questions

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 left-handed or right-handed, 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 left-handed?
- If you randomly choose a female from the people you surveyed, what is the probability that she is left-handed?
- What is the odds ratio of choosing a left-handed
**female**? - What is the relative risk of choosing a left-handed
**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 = 0.54
- Probability of Green Cat – A/(A+B): 40/60 = 0.67
- 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) = 1.71

- Skim through at least one of the following articles on left-handed vs. right-handed 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?