Frequently Asked Questions

Contained below is a list of commonly asked questions. Before <a href="/contact">sending us a message</a>, check to see if your question(s) are already answered below.

Acceptance Sampling (7)

Check out Practical Acceptance Sampling: A Hands-On Guide, Second Edition. 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.

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.

Absolutely! 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.

Our calculators have been validated by our own extensive testing. Internally our calculators use tables which are identical to the ones specified by the standards. We have launched our calculators in the year 2000 (see In the past 23 years the calculators have been used and scrutinized by thousands of users (including government agencies and many medical and pharmaceutical companies) who often double-check our results against the tables.

Accounts & Billing (5)

No, sorry. We only accept payment via PayPal, which is available in 203 countries. Payment using PayPal can be done easily and quickly with any VISA, MasterCard, American Express and other credit cards or debit cards.

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Website (5)

Kindly check your spam folder. Occasionally, spam filters flag our email as spam. If you still can’t access your account, please contact us by using the contact form.

Sure! Just go to your user page, click on the Edit tab, enter a new username, and hit the "Save" button.

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.

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