Parameter Estimation Exam

	Parameter Estimation Exam

Which method of parameter estimation is the most accurate?
Probability Plotting
Hazard Plotting
Maximum Likelihood Estimation
Matching Moments
Before the results of parameter estimation are used to predict reliability, what should be done?
Failures should be verified
The goodness of fit of the chosen distribution should be verified
Parameter validation
All of the above

Given the following data, which distribution does not provide an adequate time to fail model? A "+" indicates the item was removed from testing prior to failing.

15	27+	36	42	60+
18	31	40+	54+
18.5	33	41	60+

Lognormal
Exponential
Weibull
Normal

Probability plotting involves obtaining a linear form of
The probability density function
The hazard function
The failure rate function
None of the above
Given 4 units were tested for 100 hours without failing and an additional unit failed after 93 hours of testing, estimate the mean time to fail assuming an exponential time to fail distribution.
49
98.6
93
None of the above

Given the following data, and using the Weibull distribution, what is the lower 95% confidence limit for the time to fail at 99% reliability? A "+" indicates the item was removed from testing prior to failing.

15	27+	36	42	60+
18	31	40+	54+
18.5	33	41	60+

1.708
7.993
14.218
None of the above

Given the following data, and using the Weibull distribution, what is the lower 95% confidence for reliability at time = 10? A "+" indicates the item was removed from testing prior to failing.

15	27+	36	42	60+
18	31	40+	54+
18.5	33	41	60+

0.8266
0.8540
0.8891
None of the above

Given the following data, and using the Weibull distribution with a shape parameter of 3, what is the lower 95% confidence limit for the time to fail at 99% reliability? A "+" indicates the item was removed from testing prior to failing.

15	27+	36	42	60+
18	31	40+	54+
18.5	33	41	60+

8.453
9.112
10.59
None of the above

Given the data below, and a lognormal distribution, what is the lower 90% confidence limit for the time to fail at 80% reliability?

5	57+	186	399
18	81	240+	460+
28	133	441	460+

13.72
18.95
24.77
24.87

Given an exponential distribution, and given 4 units were tested for 100 hours without failing and an additional unit failed after 93 hours of testing, determine the lower 90% confidence limit for the time to fail.
185 hours
127 hours
235 hours
271 hours