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Flashcards in RESS - Survival analysis Deck (7)
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1
Q

What kind of data is required in survival analysis?

A
  1. The time a person enters the study

2. The time the person leaves the study (may be due to death; asking to leave; losing track of person)

2
Q

What is ‘censoring’ in survival analysis?

A

If a person leaves the study before the event occurs or enters the study after the start of the study

Survival data may be right or left censored:

Right - people in the study did not reach a failure before the end of the study e.g. a study looking at a new drug to treat HIV, right censored data will occur if the study participants die of other non-AIDS causes

Left - not certain what happened to people before they entered study e.g. people with the disease when study starts

3
Q

Define: survival function

A

The chance of survival until a certain time

4
Q

Define: hazard function

A

The chance of instantaneous failure at any one time

5
Q

What does the Kaplan-Meier plot show?

A

Survival as a series of steps

It steps down every time a failure is observed

6
Q

What tests can survival data be examined with?

A

Log-rank test

Cox proportional hazards modelling

7
Q

What does the log-rank test compare?

A

The survival functions between 2 groups