Import from China

Types of Sampling for Product Quality Control

Importing products from abroad gets complicated, and using a sample picking service to measure product quality can make a world’s worth of difference. Having someone who can physically inspect products can bring peace of mind that everything is running smoothly.

Several types of sampling exist, but not all will apply to every product. Some products can have multiple sampling methods done, and others only have one that works. This process can be overwhelming, but that is why we are here to help you understand the sampling process and know what to look for in a company that offers these services.

What is Sampling?

The inspection and study of product batches by a professional auditor or researcher is called sampling. This information then helps determine whether or not it meets the pre-defined standards. The purpose of this inspection is to maintain quality control over your products.

Quality control is critical for making customers happy and wanting to come back. A sampling plan statistically lays out when to reject materials or products. Once a somewhat small number of products from a batch go through testing, the number of defective items determines acceptance or rejection.

Types of Sampling

There are many ways a company performs these inspections, and the type of sampling depends on the products and other factors. The following are just a few of the methods used for product quality testing:

1. AQL Inspection

Acceptance Quality Limit, or AQL, is a standard that focuses on the quality level of an item compared to the ‘worst tolerable.’ When testing surpasses this number, it makes the entire batch defective. The majority of companies have different limits for minor, major, and critical defects.

AQL has two critical components to determine where limits should be. First, it shows how many samples should go through the picking and inspection process among a batch—secondly, it figures out the boundary between what is acceptable and what is not with defective products.

Companies usually tend to choose AQL inspection over other types of sampling. Most of the time, these companies set the limits as follows:

  • 0% – critical defects with potential for harm or not up to regulations
  • 5% – significant defects that most consumers would not accept
  • 0% – minor flaws may not fall in with every product specification, but most consumers would not notice or mind

Here is an informative video that goes more in-depth about the process and how to use an AQL table.

2. Incoming Quality Control

IQC (Incoming Quality Control) is incredibly important for long production chains. When sourcing products, you need to ensure the consistency and quality of even the materials before work begins on any assembly. In the cases of previous quality issues, a new supplier, the sale of lab-tested products, and items requiring expensive material, you should go with an independent IQC.

A benefit of using this sampling type is that your customers receive legitimate, well-made products and are likely to return. IQC sampling instills confidence in your business, increases your position in the market, and builds a positive brand.

Giving a list of requirements for your products’ best quality is helpful to your supplier, making it even more likely that your products will pass the tests. There are many variations of this plan, and each one suits a different situation.

3. Continuous Sampling

Sampling products continuously is best for identical products going through the same process. Also, the quality of the items should have an established, stable level of quality. This type of inspection is quick, and you will have results in no time at all.

There are a few phases that products go through during continuous sampling.

  • Every single product goes through testing until meeting a level of acceptable quality.
  • Then, only some items have checks, and it is at random.
  • When finding a defective item, screening resumes.
  • If the test keeps finding defective units, the manufacturing process needs improvement, or you need to find the exact source by setting up more in-depth tests.

4. Other Types

When an item has an easily fixable defect, a ‘rectifying’ sample plan accounts for changes made during the inspection. If an assessment of this kind fails, the entire batch then goes through the tests as well.

Sometimes, importing sensitive products such as medicines or vehicular parts should have an ‘acceptance on zero’ sampling plan. With this plan, there are no inspection stages because the whole batch’s rejection immediately follows the finding of one defect. Tests like this are best for items susceptible to legal complications if defective.

Using a plan with more specific ‘variables’ provides a more in-depth look into inspection results. Sometimes, a combination of different types of sampling will give you the information you need to ensure the quality of imported products.

Factors to Consider

When choosing a quality control service, it is essential to pay attention to several characteristics of the company you are considering to hire. Having a considerable balance of these traits shows that the company truly cares about quality.

1. Available Services

Some companies that perform these quality inspections have options for services they can provide with a higher budget. However, full assessments, pre-shipment inspections, and in-production inspections are essential, and an honest, reputable company will offer each of them.

Something else to think about is whether or not the company specializes in or at least offers sampling services for your industry. Confirm with the company what their specialty is, and get recommendations of which services help you the most.

2. Account Management

A trustworthy company will pair you with an account manager to keep in touch with throughout inspection. This point of contact notifies you of any problems and makes changes on their end. This efficiency allows for only minor production delays.

3. Reports and Results

Before you put down money for anything, get clear answers on how long the inspection and report generation will take. These reports contain not only their findings but also pictures of products and defects found. Many companies provide suggestions on fixing issues.

If an inspector discovers an issue, you can either accept them as is or ask your inspection company to collaborate with the supplier to fix things. In the case of a supplier not meeting your expectations, an excellent inspection company can provide an arrangement for product support.

4. Pricing

The last thing to consider with this sort of company is how much they ask you to pay. Generally, trustworthy companies charge anywhere from $200-$300 per person per day. Any less than this is questionable. Lower pricing also means it is likely that either the inspectors are underqualified or underpaid.

Your inspection may have a lower or higher cost due to circumstances such as travel for the inspector or not needing certain services. However, when it comes to the final price, it should include all of the following: a product inspection report, sampling, and photographs. Any company trying to charge you extra for those things should get a red flag.


Many types of sampling can help your company maintain the standards and quality you expect from your products. From AQL inspection to rectification, there is always a way to test how things are coming out, even if you have to hire a third party to go abroad.

The way Jonble handles sampling is unique. Instead of making their report from a random sample they inspect, we pick them and send them to you. We send a qualified expert to the factory, and they choose an item at random, right off the production line. The product is then sent directly to you.

If you need a sampling of your imported products but want to see them in person, this type of product testing is an excellent choice. No matter what kind of quality control inspections you need, we have you covered. Contact us to find out more or to get started.