Frequently Asked Questions

Check out the second edition of Practical Acceptance Sampling: A Hands-On Guide. Written by Prof. Galit Shmueli (creator of SQC Online), the book is a concise introduction to the inspection of products and services for quality assurance using statistically-based sampling plans.

Methods are illustrated using SQC Online, Microsoft Excel, and online calculators.

There's an e-book version available, as well as a printed book. Both are available at Amazon.com.

Try it free: Download the first chapter.

Yes. Applying a constant plan that does not take into account the history of batches is useless. The MIL-STD-105E switching rules and MIL-STD-1235C switching rules are an integral part of the sampling scheme.

Yes. Although the military standard itself was phased out in 1989, it's civilian counterparts, ANSI Z1.4 or ISO 2859 (which are essentially the same) still exist. In practice these sampling plans are widely used by many industries.

Yes. Some of our users apply acceptance sampling to processes such as auditing applications, checking errors on invoices, etc.

The problem lies in correctly using the tables. We suggest reading the standards carefully, and especially the legend and footnotes at the bottom of the particular table.
One common mistake, when arrows are present in the tables, is not adjusting the sample size according to the arrow. This is just one example.
Using our calculators is a safer alternative to the error-prone usage of the printed standards.

Here's more information about acceptance sampling and control charts.

Note: We also offer a free access program.

Apologies, but the answer is no. We provide an "Statistical Quality Control in the Cloud" service. You can access our calculators from any Internet-connected device worldwide.

A few account types are shared by multiple users. In order to protect these accounts, users are not able to update the account's email. If you require any assistance, just send us a message.

Yes. Just go to your user page, enter a new username, and click "Save".

To make it easy to manage your subscription, all users in a multi-user subscription share the same username and password. The account manager (the person who subscribed) is responsible for managing the account.

At this time we do not offer any account upgrades.

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