+-------+-------------------+
| cd4   | R Documentation   |
+-------+-------------------+

CD4 Counts for HIV-Positive Patients
------------------------------------

Description
~~~~~~~~~~~

The ``cd4`` data frame has 20 rows and 2 columns.

CD4 cells are carried in the blood as part of the human immune system.
One of the effects of the HIV virus is that these cells die. The count
of CD4 cells is used in determining the onset of full-blown AIDS in a
patient. In this study of the effectiveness of a new anti-viral drug on
HIV, 20 HIV-positive patients had their CD4 counts recorded and then
were put on a course of treatment with this drug. After using the drug
for one year, their CD4 counts were again recorded. The aim of the
experiment was to show that patients taking the drug had increased CD4
counts which is not generally seen in HIV-positive patients.

Usage
~~~~~

::

    cd4

Format
~~~~~~

This data frame contains the following columns:

``baseline``
    The CD4 counts (in 100's) on admission to the trial.

``oneyear ``
    The CD4 counts (in 100's) after one year of treatment with the new
    drug.

Source
~~~~~~

The data were obtained from

DiCiccio, T.J. and Efron B. (1996) Bootstrap confidence intervals (with
Discussion). *Statistical Science*, **11**, 189â€“228.

References
~~~~~~~~~~

Davison, A.C. and Hinkley, D.V. (1997) *Bootstrap Methods and Their
Application*. Cambridge University Press.
