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Methods&Metrics: Methods & Metrics for Product Success
Complete List of Guideline Documents
Test, Analyze, and Fix (TAAF)
Principal Risk Areas
Measures of Effectiveness
Follows Tri-Service TAAF Techincal Brief, January
Part of Integrated Test Program
2 to 10 production Units Under Test (UUT) based
on cost and complexity trade-off.
UUTs and test facilities conditioned/groomed (burn-
in, screened, etc. prior to testing.
Test environments based on worst case mission profile extremes.
As a minimum, includes vibration, temperature,
shock, power cycling, input voltage variance, and
output load variance.
Ratio of test time at vibration and temperature
extremes to total test time
Predicted Mean Time Between Failures (MTBF)
1.25 x required MTBF; growth slope
0.5; 100 hrs
proofing time; 30% predicted MTBF = starting
Statistical model best used for determining
satisfaction of early exit criteria.
Provides only unbounded minimum MTBF.
Goodness of Fit analysis used to plot cumulative
Begin TAAF early in EMD phase.
Test time for each UUT within 50% of average time
Actual growth slope
planned growth slope.
Data collection and failure analysis require extra
Monitor uncontrolled environments; supplement
with controlled simulation.
Use random vibration to simultaneously simulate all
mission profile vibration extremes for multi-
Continuously monitor all environments.
Test severity/environments reevaluated for
effectiveness if insufficient number of failures are
Minimum of one mission profile of test time to verify
Program Data Sources
Reliability growth plots
Failure reports and corrective actions
Configuration (as-built vs. as-tested)
Environment (operational vs. test)