The Probability of Death
In practice, one might use the model obtained at the end of section II
to assign probabilities of death while in ICU to new patients as they are
admitted to ICU and use the estimated probabilities along with other
considerations to determine when to discharge these patients.
- Use the current model to compute an estimate
of:
- A high-risk patient has an estimated probability of death
greater than
. List the top 10 high-risk
patients sorted in decreasing order according to their estimated
probability of death. From left to right, with 1 line per patient,
your list should include the values for:
or the other variables included in your final model.
Use the column headings ID, AGE, SEX, etc. rather than
. Are you surprised by anything on this list? What is
the value of the response variable for the people in the list ?
- For your final model, plot
as a function of age, keeping
other variables fixed at some level. Compare different curves and
comment on the ones you find to be informative. For example,
you may want to plot
as a
function of age when the levels of the other variables are low.
This would correspond to relatively healthy patients. You may also
want to try getting
for different values of LOC (for
example), and
try plotting them versus age on one plot. Please indicate the levels
you used for the different factors.
- Find the 95% confidence interval for the relative risk
between two ages keeping all other
variables fixed at some level. Specifically, use ages of 60 and 80.
What are the estimates of
and
?
Interpert
these 3 quantities. Explain how you calculate the standard error, and
what distibution you used. Indicate the levels of the different
covariates.