Chapter 5

Question 1

What is survival data?

Answer 1

Its the data to an end point

Question 2

When presenting survival data, when do you need to recalculate the percentage (proportion) of survivors?

Answer 2

Each time an individual dies or reaches completion/end point

Question 3

how do you find the median in survival data?

Answer 3

you draw a line form 50%

Question 4

why is the mean rarely calcualted in survival data

Answer 4

because it requires that you know the time for every individual (Even censored individuals)

Question 5

What does the poisson distribution do?

Answer 5

counts individual things (discrete) in an amount of time and/or space

Question 6

What is the only parameter in the poisson distribution?

Answer 6

lambda, the mean

Question 7

what is the mean in the poisson distribution?

Answer 7

The mean is the
average expected
number of events in
the given time or
volume of space.
But the actual # of
events is assumed to
vary due to chance.

Question 8

The Poisson

distribution predicts

Answer 8

how often you’ll
observe any
particular number of
events or things,
assuming that they
occur randomly.

Question 9

how does the poisson distribution differ form binomial distribution?

Answer 9

there is no upper limit
not a proportion
x axis is always number counted

Question 10

Poisson distribution assumptions

Answer 10

Events occur randomly
• ‘’ ‘’ independently
• observing an event
does not change the
probability of
observing it again.
• Average rate doesn’t
change over time
• Accurate observations
• Events counted only once

Question 11

Due to these assumptions, the Poisson distribution is best applied to

Answer 11

systems with a large number of possible events, each of which is rare.