Statistics 102H: FPP (or FPPA) Freedman's book on Statistics
Statistics 102H: FPP (or FPPA) Freedman's book on Statistics
Administrivia
email me your first part of your project ASAP
turn back projects
Discuss homework: page 24.
I won't be here Wednesday. (My 101.5 year old grandmother died
this weekend.) Chua will be filling in for me.
Chapter 16: Law of averages
What the "Law of averages" is not:
"number of heads approximately equals n/2"
No, that is too accurate
Look at graph on page 275
It keeps growing.
Sketch a log-log plot. Helps handle large numbers
Ok, then, what is it?
"fraction of heads approximately equals 1/2"
This is easier to get right
Look at graph on page 276
Sketch a log-linear plot.
More exact form of law of averages is discussed in chapter 17 (Chua
will cover it next time). Namely, what plot keeps it from dieing out
but also keeps it from going to infinity? Answer is
(count-.5n)/sqrt(n). But that is next time, and this is this time.
Abstraction: The box model
How can we generalize this to more interesting situations?
lose the extras:
Did you find subjects in the gym?
What floor were they on?
Did could the answer: tiard, exhusted, refreshed, etc
Who where they?
What where their names?
How many were there in total?
Keep essentials:
What numbers (exhausted=3)
Frequency (oops hard to determine)
total number of draws
In other words: Think if putting tickets in a box
what number to write on tickets?
how many of each kind?
how many draws?
Called box model. Goal: aproximate it as carefully as you
can.
What about this box?
In science, the question is: which box are you drawing from?