Acceptance sampling is a statistical method used to determine whether or not a batch of a product or service is acceptable for use. In other words, it’s the act of sampling a product to estimate its quality.

In this post, we will discuss extensively what acceptance sampling is and when it is applied.

What is Acceptance Sampling?

Acceptance sampling is a type of quality control in which a certain number of items are sampled from a batch and tested for compliance with specific requirements. It can be used to test the quality of manufactured goods or materials, such as metal bars or concrete.

It can also be used to test the performance of a product after it has been installed, like a piece of software that was supposed to perform one function but now performs another. The goal is to ensure that all products meet a certain standard, which could be different depending on the industry.  For example, if you’re testing copper bars, you might want them all to have a maximum amount of impurities. If you’re testing software performance, you might want it to run at least 20% faster than previous versions.

Read: Probability Sampling: Definition, Types, Examples, Pros & Cons

To determine whether each piece meets these standards, sample sizes must be large enough so that they can accurately represent what’s happening overall. If the results show that the samples meet your standards, then you are able to proceed with production.

If not, then you must find out why the product did not meet your standards and make any necessary adjustments before proceeding with production. The larger your sample size is (as long as it’s still manageable) and the more samples you take from each batch (as long as this doesn’t lead to too much time wasted), the more accurate your results will be. 

Therefore, in order for acceptance sampling to work effectively, there must be clear standards in place for what constitutes a defect. These standards are usually determined by industry-specific regulations or laws set by governing bodies like the Food and Drug Administration (FDA) or Consumer Product Safety Commission (CPSC).

Read: Convenience Sampling: Definition, Applications, Examples

History of Acceptance Sampling

The history of acceptance sampling dates back to a time before mass production. In fact, it was developed as a way for manufacturers to check their work as they created products manually. 

It is a form of quality control and is used to ensure that each batch is of high quality before it is sold. Acceptance sampling was first developed by Walter A. Shewhart, an engineer at Bell Laboratories in New Jersey. 

He worked on the project along with statistician William Edwards Deming and physicist W. Edwards Deming. Shewhart published his work on acceptance sampling in 1931 in a paper titled “Statistical Method from the Viewpoint of Quality Control.”

Read: Purposive Sampling: Definition, Types, Examples

The idea was that if a worker made one bad product every 100 times, he would be fired, so he would make sure to make 99 good products in order to keep his job. This is called “100% inspection.” 

You can imagine how difficult this would be if you’re creating thousands or even millions of products. So instead, they came up with an alternative method: accept samples of items being made and reject those that don’t meet your standards. 

This is where acceptance sampling comes in and allows you to test each item before you accept it into your inventory for sale or use by consumers.

Purpose of Acceptance Sampling

The purpose of acceptance sampling is to reduce the likelihood that defective parts will be included in a final product. By using this method, companies can ensure that only high-quality products are sold to consumers which makes them more likely to make repeat purchases.

Acceptance sampling allows companies to determine if their product meets their standards before they begin mass production or distribution. If it does not meet their standards, they can reject that batch and start anew instead of continuing down the path towards producing something less than satisfactory quality-wise.

Read: Quota Sampling: Definition, Types, Pros, Cons & Examples

Types of Acceptance Sampling

There are three main types of acceptance sampling: single sampling plan, double sampling plan, and sequential sampling plan.

1. Single Sampling Plan

A single sampling plan involves choosing a sample from each lot and testing it to see if it meets a certain quality threshold. If it does not meet the threshold, the entire lot is rejected. This type of plan is commonly used when inspecting products that are manufactured in small batches (e.g., semiconductors) and are made using highly automated processes that make it difficult to inspect each individual unit before assembly.

2. Double Sampling Plan

A double sampling plan involves choosing two samples from each lot and testing both to see if they meet a certain quality threshold. If at least one sample meets the quality threshold, then the entire lot will be accepted. This type of plan is commonly used when inspecting products that are manufactured in large batches (e.g., pharmaceuticals) but where there are no automated processes involved in producing them (e.g., printing).

3. Sequential Sampling Plan

This method involves choosing several samples from a given population at random and testing each one until one fails to meet required standards; when that occurs, all subsequent samples are tested until another sample fails to meet required standards (at which point all subsequent samples are rejected).

Read: Consecutive Sampling: Definition, Examples, Pros & Cons

Does Acceptance Sampling Work?

The short answer is yes. Acceptance sampling has been a part of manufacturing for over 100 years, and it’s still used today because it works.

The idea behind acceptance sampling is simple, rather than testing every single unit produced, you test a small sample of units instead. The idea behind this is that if the percentage of defective units in your sample is low enough (usually around 5%), then you can be pretty sure that most of your product will be good, even if there are some bad units mixed in with all the good ones.

Acceptance sampling works because it allows you to reduce costs by eliminating the need to test every single unit. It also helps ensure that the quality level of your product meets expectations and standards which means fewer returns and customer complaints.

When to Use Acceptance Sampling

Acceptance sampling can be used in many different ways, including:

• Determining whether or not a batch of products should be manufactured
• Testing the effectiveness of new manufacturing processes and equipment
• Checking if there are any issues with existing products
• To determine whether a product conforms to specifications and standards
• To check that an assembly process has been completed successfully
• To test samples of products before they are sold to consumers

Read: Rejection Sampling: Definition, Types, Examples

This approach can be used in a variety of situations, but it’s especially useful when there are multiple defects that can be found with a single sample. For example, if you’re producing cereal boxes, you can use acceptance sampling to determine whether or not all of your cereal boxes have been made to the same specifications. 

If they have, then you’ll know that every box contains roughly the same amount of cereal and sugar as every other box. If not, then you’ll know which boxes need more sugar added before they can be considered acceptable for sale.

Read: Snowball Sampling Guide: Types, Examples, Pros & Cons

Advantages of Acceptance Sampling

Acceptance sampling can be used for testing both the physical and functional properties of products. It can also be used for testing samples from customers. Advantages of acceptance sampling include:

1. Reduced inspection costs by reducing the number of items inspected
2. Increased flexibility in production schedules since fewer items need to be inspected
3. Reduced inspection time for each item due to less number of items being inspected at one time.
4. You can use it for almost any type of product or service
5. It doesn’t require much training
6. It helps manufacturers determine whether their products meet certain minimum standards for quality

Disadvantages of Acceptance Sampling

The disadvantage of acceptance sampling is that it may not provide enough information about how well your process works overall.

1. The samples are often representative of only a small portion of the lot. For example, if you take 10 pieces from every 100 boxes on a pallet, you may find that those 10 pieces meet your standards but that the other 90 pieces do not. This means that you have wasted time and money on what could have been a perfectly good product because you didn’t test enough units in order to ensure quality assurance throughout your production run.
2. Testing can be subjective and expensive depending on how it’s conducted (e.g., if someone needs training before being able to perform tests properly).

Read: Multistage Sampling: Types, Applications, Pros & Cons

Examples of Acceptance Sampling

Example1 

For example, if you’re manufacturing a new line of flannel shirts and want to sell them on Amazon, you could conduct an acceptance sampling test before offering them for sale. You might choose 100 customers at random, ship them each a shirt from your new line, and ask them to rate their experience with the shirt on Amazon’s website. If fewer than 10% of customers give your shirt less than 4 stars out of 5 stars (or any other rating system), then you can rest assured that your shirt meets the quality standards necessary for selling it through Amazon’s marketplace.

Example 2

For example, if you’re making 5,000 widgets and you know that there are 10 defective units in every 1,000 units produced, then you could set up a testing procedure where only 100 widgets are tested for each batch. If there were no defects found in those 100 widgets, then the entire batch would be accepted as acceptable but if even one defective widget was found, then all 5,000 would be rejected.

Example 3

For example, if you’re manufacturing widgets and want to make sure they’re all exactly three inches long, you could buy some of your manufactured widgets and measure them to see how many are close enough to three inches. If there’s only one outlier (a widget that’s over three inches), then you know that your production process is working as expected.

If, on the other hand, there were ten outlying widgets among the twenty purchased for measurement, then you’d know that your production process needs some attention, it’s likely producing many more than just one defective widget in every twenty produced.

Conclusion

Acceptance sampling can be used in a wide variety of industries, from manufacturing to retail. Generally speaking, acceptance sampling is used to determine whether or not a product meets the quality standards required by the customer.