Follow-Up & Survival Analysis Flashcards
7 cards from real CET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Follow-Up & Survival Analysis flashcards as text
What does the survival function S(t) represent in reliability analysis?
Answer: The probability that a component survives beyond time t
S(t) gives the probability that a component or system has not failed by time t.
If a component has a constant failure rate λ = 0.002 failures/hour, what is its MTBF?
Answer: 500 hours
MTBF = 1/λ = 1/0.002 = 500 hours for a constant (exponential) failure rate.
In the 'bathtub curve,' which region is characterized by a decreasing failure rate?
Answer: Infant mortality period
The infant mortality (early failure) region shows a decreasing failure rate as weak units are screened out.
The hazard function h(t) in reliability analysis represents:
Answer: The instantaneous failure rate given that the item has survived to time t
h(t) is the conditional instantaneous failure rate for units that have survived up to time t.
What is 'right censoring' in a survival analysis context?
Answer: The study ending before all items have failed
Right censoring occurs when the observation period ends before a unit fails, so the exact failure time is unknown but known to be beyond the observation time.
The Kaplan-Meier estimator is primarily used to:
Answer: Estimate the survival function nonparametrically from censored data
The Kaplan-Meier method estimates the empirical survival function and correctly handles censored observations.
The exponential reliability model assumes which type of failure rate?
Answer: Constant failure rate (memoryless property)
The exponential distribution's defining property is a constant hazard rate, which makes past operating time irrelevant to future failure probability.