QA Interview Questions

Here are some of my favorite QA interview questions and answers for quality professionals.

During the QA interview, I keep in mind that quality professionals’ tools are transferable. They can take their tools from one company to another company in an entirely different industry and be productive.

When I’m interviewing Quality Professionals, my QA interview questions focuses more the interviewee’s quality tools and how they used those tools.

ISO 9001 Questions

For Quality Assurance Managers, I expect they previously managed an ISO 9001 company. During the QA interview questions, they should be able to describe the ISO 9001 requirements. They should roughly know the 8 principles of ISO 9001.

For Quality Engineers they should have worked in an ISO 9001 environment. They should know the basic systems such as document control and corrective action.

What is your track record on ISO 9001 non conformities?

If they were the management representative have them describe the non conformities found during the ISO 9001 surveillance audit. Can the interviewee describe the corrective action implemented for the non conformity? Does the corrective action seem reasonable? Be suspect of individuals who state they have zero non conformities.

SPC Questions

What does SPC do? What computer programs have you used for SPC? What processes have you set up with SPC. When sample size is 1 how do you determine the range?

In a nutshell, the SPC tool shows when a process is out of control. There are many computer programs but one of the best is Hertzler. With regards to the SPC processes, there are an unlimited number of named processes.

Durig these QA interview questions, I look for their reasoning behind using SPC on those processes. Did they find certain unstable processes? Did they reduce inspection sampling with SPC? Did they reduce process variation with SPC? Did they teach operators to use it? Did they share charts with customers?



When sample size is 1 how do you determine the range for SPC?

This question provides extensive insight into the interviewee understanding the math behind SPC. For most SPC, sample size one is not used. If sample size of one is used, the range is determined by the average differences from the previous readings. If they refer to a moving range chart, that answer is satisfactory.

What is CpK? What is the main assumption behind the statistic? What is the equation?

Quality professionals use the statistic CpK to give a single digit number that represents how well a process fits an engineering specification. A CpK number of 2 means the process is 6 sigma capable. The main assumption behind the statistic is that the process data is normally” distributed“.

The equation is:
CpK = The lower value of these 2 equations
(high spec – process average) / (3 * standard deviation)
(process average – lower spec) / (3 * standard deviation)

Customer Interface

Quality professional addresses customer’s quality problems. These QA interview questions lets me see their experience with customer interface.

What were the topics of conversation? How did the interviewee treat the customer? How did the interviewee calm the customer when there are quality problems.

Here I need to see an urgency from the interviewee. It is important that the quality professional deals with the quality problem promptly. They quickly call the customer or send an email when there is a problem.

Have you written formal corrective action letters to customers? After initiating corrective action, what is the most important thing to do?

Formal corrective action letters should follow the 8D format. Quality professionals should know this format. The most important thing to do with corrective action is follow up. Too many times I have seen corrective actions were documented, actions were taken but 2 weeks later the permanent action disappears. Follow up is the most important thing to do for corrective action.

Audits

Unless you absolutely know that the employee is doing something that will cause non conformities, do not take any action against the employee. Discuss the issue with the employee for more input. Do not take any disciplinary action. Do not correct them on the spot. You document the findings for later review. The employee may actually have a better process than the procedure. See below for more QA interview questions.

Design of Experiments (DOE)

Most QA professionals do not know DOEs. I’m wary of those who make stuff up on these QA interview questions. A DOE is a systematic method of conducting engineering tests. If there are multiple factors being studied, a DOE will find the principle factor and interactions with a minimal amount of engineering runs. The main statistic behind a DOE is the f test.

Reliability

Software

During the QA interview, most will reply with Microsoft Excel. It’s a benefit to have those individuals who have used Minitab, JMP, SAS and / or Hertzler. It shows they have been exposed to other software and they can help the company select sound software tools for improvement.

Gage R&R

A Gage R&R, (reproducability and repeatability) study exposes the measurement error within any measurement system. It tell us how much error the operator is contributing, how much error the instrument is contributing and the amount of natural error. It is desirable to have machine and operator error less than 20% of the total error.