RAM RAM Data Analysis & Statistics 2

Question 1

What is the Kaplan-Meier estimator used for in reliability analysis?

Accepted Answer

Non-parametrically estimating the survival function from life data including censored observations

Answer

Predicting future spare parts demand

Answer

Calculating the optimal preventive maintenance interval

Answer

Fitting a Weibull distribution to accelerated test data

Question 2

What is the median rank method used for in reliability probability plotting?

Accepted Answer

Assigning cumulative failure probability estimates to ordered failure times for plotting on probability paper

Answer

Estimating the average failure rate of a fleet

Answer

Calculating the confidence interval around an MTBF estimate

Answer

Determining the minimum sample size for a reliability demonstration test

Question 3

What does a Q-Q (quantile-quantile) plot assess in reliability data analysis?

Accepted Answer

How well the observed failure data fits a hypothesized theoretical distribution

Answer

The cost distribution of spare parts over time

Answer

The relationship between temperature and failure rate

Answer

The number of censored observations in a dataset

Question 4

What is the chi-square goodness-of-fit test used for in RAM statistical analysis?

Accepted Answer

Testing whether observed failure frequency data is consistent with a hypothesized theoretical distribution

Answer

Estimating Weibull parameters from field data

Answer

Calculating confidence intervals for availability estimates

Answer

Optimizing spare parts reorder points

Question 5

What does a confidence interval around an MTBF estimate communicate to a reliability engineer?

Accepted Answer

A range of values within which the true MTBF lies with a specified probability, reflecting uncertainty due to limited sample size

Answer

The exact true MTBF value of the population

Answer

The minimum acceptable MTBF per the contract specification

Answer

The range of repair times observed in the field

Question 6

What does assuming a constant failure rate (λ = constant) imply about the underlying probability distribution?

Accepted Answer

The failure times are exponentially distributed with no aging or infant mortality effects

Answer

The failure times follow a Weibull distribution with β = 2

Answer

The failure times follow a normal distribution

Answer

The failure rate is increasing linearly with time