Articles tagged Acceptance sampling

An inspection in which the decision to accept an item (often a lot) depends on the inspection results. Acceptance sampling provides a cost-effective and statistical-based assessment of a lot of items.

by Hemant Urdhwareshe Leave a Comment

Reliability Testing Sampling Plans Part-2 (PRST and Fixed Length Plans)

Dear friends, Institute of Quality and Reliability is happy to release this video on Reliability Testing Sampling Plans. In this is Part-2 of the video, Hemant Urdhwareshe has explained the Probability Ratio Sequential Test (PRST) and Fixed Length plans from MIL-Handbook-781. These include illustrated explanation of the plans and applicability.

We are sure, viewers will find this video useful!

Earlier, we released part 1 of the video, in which Hemant explained the concepts of sampling risks and operating characteristics (OC) curves.

We also suggest viewers to see our related videos on Hazard Rate and related concepts for better understanding of this video.

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by Hemant Urdhwareshe Leave a Comment

Reliability Sampling Plans Part-1 (Basic Concepts)

Dear friends, Institute of Quality and Reliability is happy to release this video on Reliability Sampling Plans. In this is Part-1 of the video, Hemant Urdhwareshe has explained the basic concepts in Sampling plans. These include Sampling Risks and Operating Characteristics. We are sure, viewers will find this video useful!

We will release part-2 of the video where Hemant will explain Fixed Length Reliability Test Plans and Sequential Test Plans (PRST).

[Read more…]

by Ray Harkins Leave a Comment

A Primer on Acceptance Sampling Plans

In modern manufacturing, ensuring product quality is paramount. One of the fundamental tools employed to maintain quality standards is sampling plans. These plans provide a systematic approach to inspecting a subset of items from a larger batch, allowing for efficient and reliable decision-making regarding the acceptability of the entire lot.

In this primer, we probe the essentials of sampling plans, their types, and the trade-offs between sampling and 100% inspection. Because of their ubiquitous use in manufacturing, we will more closely examine attribute sampling plans, including single, double, and multiple sampling plans, and their applicable industry standards.

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by Fred Schenkelberg Leave a Comment

OC Curve with Hypergeometric Method

The operating characteristic curve is used to understand lot sampling plan. It graphically provides a relationship between the unknown lot’s defect rate (or total) and the probability of the specific sampling plan to accept the lot. Very good plans discriminate between good and bad lots. Poor plans may accept bad lots or reject good lots to easily. [Read more…]

by nomtbf Leave a Comment

AQL decision

Recently I received a question related to setting an Acceptable Quality Level (AQL) for a sampling of fielded electricity meters. The question was on how to select the right AQL for use with the sampling plan. I was not sure from the question if the sample would determine if the population would be replaced or not (expensive), or simply an experiement to determine how the meters are doing after 15 years of service (information only). [Read more…]

by Fred Schenkelberg 5 Comments

Sequential Sampling by Attributes

There a few different ways to sample a lot (or group) of material to determine if it has an acceptably low failure rate (or proportion that are considered ‘bad’). The following is an example of the sequential sampling method, which happens to be rather efficient by generally using the fewest samples for the same risk protection. [Read more…]