First Year Dropout Calculations
If a Telcordia calculation method that supports burn-in data is selected, the first year dropout is computed using the following procedure and the burn-in data entered in the System file.
1. Calculate the failure rate for each part at time = 0.
λ1 = 1000 * λSS where 1000 is actually is 104a and a = 0.75.
2. For each part, calculate the effective operating time resulting from device, unit, and system burn-in.
To calculate the total effective burn-in time, add up the times for the device, unit, and system burn-in.
3. For each part, calculate the instantaneous failure rate at the end of the month.
To calculate the total failure rate for the unit, add up the individual failure rates for its parts.
4. For each part, calculate the percentage of cumulative failures.
To calculate the expected number of failures, use the following equation.
5. Calculate the average cumulative failure rate, which is defined as the average failure rate between time 0 and time t.
6. Stores the month and results for the failure rate, expected number of failures, and average cumulative failure rate in the First Year Dropout table.
An ancillary report, Prediction First Year Dropout, is supplied for reporting on first year dropout values in the System file.