Publication date: 11/10/2021

Nonparametric Reliability Demonstration

Use the Demonstration Explorer for Nonparametric Reliability to determine the number of units to put on test for a reliability demonstration when there is not an assumed failure rate distribution. Select DOE > Sample Size Explorers > Reliability > Nonparametric Reliability Demonstration. Explore the trade offs between time, significance, number of failures, and the number of units to test.

Demonstration Explorer for Nonparametric Reliability Options

Set study assumptions and explore sample sizes using the radio buttons, text boxes, and sliders. The curve updates as you make changes to the settings. Alternatively, change settings by dragging the cross hairs on the curve or adjusting the values in the axis text boxes.

Fixed Parameters

Alpha

Specifies the probability of a type I error, which is the probability of rejecting the null hypothesis when it is true. It is commonly referred to as the significance level of the test. The default alpha level is 0.05.

Demonstration Parameters

Parameters that are inter-related and update as you make changes.

Maximum failures allowed

Specifies the maximum number of failures allowed for a successful test demonstration.

Sample Size

Specifies the total number of units on test needed for your demonstration.

Demonstration Reliability

Specifies the probability that the item under test survives until the defined Demonstration Time of the reliability standard.

Save Settings

Saves the current settings to the Saved Settings table. This enables you to save a set of alternative study plans. See Saved Settings in the Sample Size Explorers.

Make Data Collection Table

Creates a new data table that you can use for data collection.

Statistical Details for the Nonparametric Reliability Demonstration Explorer

For a nonparametric reliability demonstration test, the demonstrated reliability is computed based on the Binomial distribution. The α quantile of the Binomial cdf can be computed by a transformation to an α quantile from the F-distribution, see Jowett, (1963).

The reliability is calculated as follows:

where

and c is the maximum number of failures allowed during the demonstration.