Overview of Nonparametric Distribution Analysis (Right Censoring)

Use Nonparametric Distribution Analysis (Right Censoring) to estimate the reliability of a product when you have reliability data with exact failure times and/or right-censored observations, and no distribution adequately fits your data. When data are right-censored, failures are recorded only if they occur before a particular time. A unit surviving longer than that time is considered a right-censored observation. For more information, go to Data censoring.

Depending on which nonparametric method you choose, you can do the following:

Estimate the percentage of items that will fail or survive at various time intervals
Display hazard plots and survival plots to view the failure and survival probabilities
Test the equality of the survival curves for multiple samples

You can also use a nonparametric distribution analysis to validate and compare the results from a parametric distribution analysis. A nonparametric distribution analysis is less efficient than a parametric analysis with an appropriate distribution model, and thus often produces wider confidence intervals. However, because a nonparametric analysis does not require fitting any distribution to your data, its results will not be adversely affected by a poor distribution fit.

When your product fails in different ways, use a failure mode analysis to evaluate the impact of each type of failure on the overall reliability. Each failure mode is assumed to be independent. By analyzing each failure mode individually, you can more easily prioritize your improvement efforts.

Where to find this analysis

To perform a nonparametric distribution analysis for right-censored data, choose Stat > Reliability/Survival > Distribution Analysis (Right Censoring) > Nonparametric Distribution Analysis.

When to use an alternate analysis

If your data include either left-censored observations or interval-censored observations, or have a varied censoring scheme that includes exact failure times, right censoring, left censoring, and/or interval censoring, use Nonparametric Distribution Analysis (Arbitrary Censoring).
Parametric methods provide more precise results and estimate more types of functions Therefore, if you can fit a parametric distribution to your data, use Parametric Distribution Analysis (Right Censoring).