# CRE Preparation Blog

A WordPress blog focused on aiding those preparing for the ASQ Certified Reliability Engineer exam. The following excepts are from the most recent blog entries. To see the full list of posts, please visit https://accendoreliability.com/creprep/, or click on one of the excepts below.

sign up to receive a weekly update from the CRE Preparation Notes on the Accendo Reliability site. We will not share your email with anyone else.

- The Informative Run Chart

The Informative Run Chart One of the very first plots of a string of data is a simple run chart. The plot of the data over time. This plot provides information related to location, trends, patterns, a … - Stratification: A Basic Quality Tool

Stratification: A Basic Quality Tool Stratification implies layers or differences. A quick test for soil composition is to place a sample of soil with water in a clear jar and give it a shake. The san … - Creating a Histogram

Creating a Histogram A histogram is a graphical representation of a set of data. It is useful to visually inspect data for its range, distribution, location, scale, skewness, etc. There are many uses … - t-test Hypothesis Testing for Means with Unknown Variance

t-test Hypothesis Testing for Means with Unknown Variance In the situation where you have a sample and would like to know if the population represented by the sample has a mean different than some spe … - Tips for Better Online Learning

Tips for Better Online Learning One of the key ideas behind the ASQ CRE certification is the need to learn enough to pass the exam. Then you are expected to continue to learn to maintain your certific … - Building a Basic Box Plot

Building a Basic Box Plot One of the first things to do when faced with a set of numbers is to plot them. A histogram is often the first choice, maybe a dot plot. Up your data plotting skills and let … - Introduction to the Delphi Method

Introduction to the Delphi Method As reliability professionals, we are in the business of estimating or forecasting the reliability performance of our product, equipment, or system. While we use a ran … - What-if Analysis

What-if Analysis What if you knew all the possible outcomes for your product’s reliability performance due to component variations, for example? What if you knew the future with enough certainty to ma … - Creating a Dot Plot

Creating a Dot Plot Graphs contain information and often tell a story. Our interpretation of the graphic can be aided or hindered by the design or style of the plot. Cleveland and McGill (1984) studie … - Building and Using Pareto Charts

Building and Using Pareto Charts You may have heard of the 80/20 rule. The idea is that 80% of the wealth is held by 20% of the population. As an Italian economist, Vilfredo Pareto made this observati … - Beware of the Type III Error

Beware of the Type III Error There is a type of error when conducting statistical testing that is to work very hard to correctly answer the wrong question. This error occurs during the formation of th … - Sample Size for Hypothesis Testing of μ

Sample Size for Hypothesis Testing of μ A common question when setting up a hypothesis test is concerning sample size. An example, might be: How many samples do we need to measure to determine the new … - The Power of a Sample

The Power of a Sample We use a sample to estimate a parameter from a population. Sometimes the sample just doesn’t have the ability to discern a change when it actually occurs. In hypothesis testing, … - Type I and Type II Errors When Sampling a Population

Type I and Type II Errors When Sampling a Population In hypothesis testing, we set a null and alternative hypothesis. We are seeking evidence that the alternative hypothesis is true given the sample d … - Single Sample Z-test Hypothesis Testing for Mean with Known Variance

Single Sample Z-test Hypothesis Testing for Mean with Known Variance In the situation where you have a sample and would like to know if the population represented by the sample has a mean different th … - AND and OR Gate Probability Calculations

AND and OR Gate Probability Calculations In system modeling and fault tree analysis (FTA) we use a set of similar calculations based on Boolean logic, the AND and OR gate probability calculations. Wit … - The Risk Matrix as a Communication Tool

The Risk Matrix as a Communication Tool Not all risks the same. Some are minor with little consequence, while others are not. Every organization or reliability program facings a plethora of risks and … - There Might be 50 Reasons to Use a Histogram (or Bar Chart)

There Might be 50 Reasons to Use a Histogram (or Bar Chart) When confronted with a stack of data, do you think about creating a histogram, too? Just tallied the 50th measurement of a new process – jus … - Is a Professional Certification Worth It?

Is a Professional Certification Worth It? The way we learn, prove our worth, and the nature of work are all changing. Professional societies are struggling to adjust to these changes. Universities and … - Using a Strip Chart

Using a Strip Chart Sometimes we just need a simple plot of a few data points. When there is scant data a histogram or box plot just is not informative. This is a great use for a one dimensional scatt …

## Course offerings

If you or your team would like a custom CRE prep course, just let me know and we’ll make arrangements to make it happen. I also teach a live 32 hour CRE Preparation course through the

ASQ Silicon Valley Section when we have at least four students. The course runs for the 8 weeks prior to semi annual exam. Learn more about the CRE at the ASQ site.