#9 lab worksheet
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- make a new folder for week 9
- files for this week:
w9edf1.m w9edf2.m w9edf3.m
- start matlab & change to the
week 9 folder
KEY QUESTION: what is the meaning of
those goodness-of-fit quantities, W^2
and r^2?
warm-up
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run each of the w9edf#.m scripts
in order. they should reproduce
professor stephens' good example
from yesterday. (with the exception
of a now corrected r^2 value.)
be sure you understand the meaning of
each of the plots.
calculate the W^2 for the data of
w9edf2.m (it should be 0.0553).
calculate the r^2 for the data of
w9edf3.m (it should be 0.9064).
STUDY #1
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w9edf1.m draws a random sample of
25 exponentially distributed (mu=1)
values. when you calculate the EDF,
it should approximately look like
the theoretical CDF F(x)=1-exp(-mu*x).
but it will not be exactly same,
and the the W^2 will be small (hopefully)
but not zero. in fact, the values of
W^2 themselves have some CDF! your
task will be to compute many different
(don't reset the random seed!) samples,
and build an EDF of W^2 values, until
it looks reasonably smooth and you can
give:
the "quartile" values of W^2 below which
you will find 25%, 50% and 75% of random
samples of 25 exp. dist. values.
also, what happens to the W^2 EDF as you
increase the number of random #s in your
sample (Nran...