Turnbull estimation method for Nonparametric Distribution Analysis (Arbitrary Censoring)

Probability of failure – Turnbull estimation method

The probability of failure provides, for each interval, the chance that the product will fail in that interval. Use this information to determine the following:
  • Which intervals have the most failures
  • Whether the failures are spread among many time intervals or concentrated among a few intervals

Nonparametric estimates do not depend on any particular distribution and therefore are good to use when no distribution adequately fits the data.

Example output

Turnbull Estimates Interval Probability Standard Lower Upper of Failure Error 20000 30000 0.002860 0.0016488 30000 40000 0.010486 0.0031451 40000 50000 0.032412 0.0054678 50000 60000 0.102955 0.0093830 60000 70000 0.170639 0.0116151 70000 80000 0.248808 0.0133481 80000 90000 0.231649 0.0130259 90000 * 0.200191 *

Interpretation

For the new muffler data, 0.248808 (or 24.8808%) of the new type of mufflers failed in the interval from 70,000 to 80,000 miles.

Survival probabilities – Turnbull estimation method

The survival probabilities indicate the probability the product survives until a particular time. Use these values to determine whether your product meets reliability requirements or to compare the reliability of two or more designs of a product.

Example output

Table of Survival Probabilities Survival Standard 95.0% Normal CI Time Probability Error Lower Upper 30000 0.997140 0.0016488 0.993909 1.00000 40000 0.986654 0.0035430 0.979710 0.99360 50000 0.954242 0.0064517 0.941597 0.96689 60000 0.851287 0.0109856 0.829756 0.87282 70000 0.680648 0.0143949 0.652435 0.70886 80000 0.431840 0.0152936 0.401865 0.46181 90000 0.200191 0.0123546 0.175976 0.22441

Interpretation

For the new muffler data, 0.954242 (or 95.4242%) of the new type of mufflers survive at least 50,000 miles.

By using this site you agree to the use of cookies for analytics and personalized content.  Read our policy