# Segment 6. The Towne Family Tree

#### Watch this segment

(Don't worry, what you see out-of-focus below is not the beginning of the segment. Press the play button to start at the beginning and in-focus.)

{{#widget:Iframe |url=http://www.youtube.com/v/y_L2THpv5Jg&hd=1 |width=800 |height=625 |border=0 }}

The direct YouTube link is http://youtu.be/y_L2THpv5Jg

Links to the slides: PDF file or PowerPoint file

### Problems

#### To Compute

1. Write down an explicit expression for what the slides denote as bin(n,N,r).

2. There is a small error on slide 7 that carries through to the first equation on slide 8 and the graph on slide 9. Find the error, fix it, and redo the graph of slide 9. Does it make a big difference? Why or why not?

#### To Think About

1. Suppose you knew the value of r (say, r = 0.0038). How would you simulate many instances of the Towne family data (e.g., the tables on slides 4 and 5?

2. How would you use your simulation to decide if the assumption of ignoring backmutations (the red note on slide 7) is justified?

3. How would you use your simulation to decide if our decision to trim T2, T11, and T13 from the estimation of r was justified? (This question anticipates several later discussions in the course, but thinking about it now will be a good start.)

### Class Activity

Kai won the $100 contest. Congratulations to him! I'll have to be more careful before I offer prizes this big in the future!