# Intro to Statistics for Forensic Science

These materials were created for “The Basics of DNA Evidence” workshop taught by the Forensic University in Spring 2022.

## Learning outcomes

By the end of the course, you will be able to

- explain what are probabilities and how they are computed in practice
- select the correct probability rule depending on the situation: product rule, addition rule or conditional probabilities rule
- describe the main fallacies when interpreting probabilities

## Syllabus

Topic |
Key take-away points |
Lecture notes |

1. What is probability? |
i) When it comes to probabilities, we do not trust our gut, we trust the formulas; ii) We estimate population probabilities from observed frequencies in samples; iii) The chosen sample is very important |
notes |

2. How do we combine probabilities? |
i) Product rule: we can calculate the probability of simultaneous events when they are independent; ii) Addition rule: we can calculate the probability of different disjoint events |
notes |

3. How do we update probabilities when new information is available? |
i) The conditional probability allows us to update a probability with new information; ii) Very important not to confuse the conditioning event as probabilities would change |
notes |

## YouTube video of the lecture

You can find the 90-minute lecture including all three topics in this link.

## Meet the instructor

Claudia Solís-Lemus is an assistant professor at the Wisconsin Institute for Discovery and the Department of Plant Pathology at the University of Wisconsin-Madison. Originally from Mexico City, she did her Undergraduate degrees
in Actuarial Sciences and Applied Mathematics at ITAM.
Then, she did a MA in Mathematics and a PhD in Statistics at the University of Wisconsin-Madison.