Corrections and Notes to Exercises
July 25, 2006
In Part III of the laboratory exercises (p.15), there were, prior to
July 25, the following mistakes:
Line 7 (item b): qnorm() should be pnorm()
[ qnorm() gives, for a given normal deviate, the cumulative probability.]
Line -2: qnorm() should, again, be pnorm()
August 2, 2006 (New versions will be posted shortly).
Part I, page 6, Exercise 6: The second ant111b should be vince111b
Part II, page 10, Exercise 4: Replace "random sample of 200" with
"random sample of 500".
Exercise 5: apply(mat,2,mean) should be apply(mat,1,mean)
Part IV, page 22, Exercise 7: Replace "simulateSampDist(numINsamp = c(4, 9))"
with "sampvalues <- simulateSampDist(numINsamp = c(4, 9))"
page 21, Exercise 5: Replace "dens <- density(twot(n=999))
with the two statements
"
d2 <- twot(n=999)
dens <- density(d2)
"
Part V, page 26, Exercise 4(b): For "age of the earth" read "age of
the universe".
It may help to explain that according to the relevant cosmological
model, the velocity of recession of any galaxy relative to any other
galaxy has been constant, independent of time. Those parts of the
universe that started with the largest velocities of recession from
our galaxy have moved furthest, with no change from the velocity just
after after time 0. Thus the time from the beginning should be s/v,
where s is distance, and v is velocity. The slope of the least
squares line provides a combined estimate, taken over all the
galaxies for which data is given.
August 16 2006
Part VI, page 29, Exercises 1-4
lngth should be length
Note that fitted() and residuals() and other such functions
are applied to model objects, i.e., for lm models, to the
output from lm(....)