Stat 135, Fall 2006
HOMEWORK 10 (due Friday 12/1)
In what follows, you will have to do lots of regressions and pick one or two that are better
than the others.
DO NOT
turn in all the regression output. The only computer output I
want to see are the relevant plots, along with a clear discussion of what they imply. The rest
of each answer should consist of a carefully written paragraph, including numerical values
from your computer work as appropriate.
You
will have to work out what’s appropriate.
1.
The dataset
chicks
was obtained from
BLSS: The Berkeley Interactive Statitstical
System
by Abrahams and Rizzardi.
Each observation corresponds to an egg (and the re
sulting chick) of a bird called the Snowy Plover. The data were taken at Point Reyes Bird
Observatory. Column 1 contains the egg length in millimeters, Column 2 the egg breadth
in millimeters, Column 3 the egg weight in grams, and Column 4 the chick weight in grams.
The object is to estimate the size of the chick based on dimensions of the egg.
a)
First you are going to regress chick weight on egg length.
Write out the usual re
gression model in terms of these two variables. Plot the data and comment on whether the
assumptions of the model are reasonable. Find the means and SDs of both variables, as well
as the correlation between them. Use the formulas you derived in HW 9 to find the slope
and the intercept of the regression line. Provide units for the slope and the intercept, and
write the equation of the regression line. Draw the regression line on your plot.
b)
Now use R to regress chick weight on egg length. Check that R produces the same
slope and intercept that you got in
a
. For each of the
t
and
F
statitics in the
R
output,
state the null and alternative hypotheses that are being tested, and state the conclusion of
the test.
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 Spring '12
 jagoda
 Linear Regression, Regression Analysis, Egg Weight, Snowy Plover, egg length, chick weight

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