Lab assignment 8 (due Wednesday, Apr. 6)

*** SLBD stands for the book "Statistics: Learning by Doing."  ***

*** SAWA stands for "Short Answer Writing Assignment"  ***

Please read lab session 11 (pages 160-172 of SLBD) BEFORE coming to class
on Monday.


I.  Answer SAWA questions 1-5, 7, 8 (in complete sentences where appropriate) 
in the lab book.

II.  Often, when measuring "failure times" or "lifetimes" of items under stress or 
subjects with some disease, statisticians use what is known as censoring.  Type I 
censoring occurs when the experiment is run for a pre-specified amount of time and 
then stopped, although some of the items may not have failed (died) yet.  Type II 
censoring occurs when the experiment is run until a pre-specified number of items 
(less than the total number of items) have failed.  In these cases, the 
items which have not failed at the end of the experiment are "censored", since 
we don't know their exact lifetimes.  Give an example of a study in which 
censoring would be necessary, explain briefly why it would be necessary, and state 
which type of censoring would be used.