# 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.

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- The Informative Run Chart

One of the very first plots to do with a string of data is a simple run plot. This plot provides information related to location, trends, patterns, and anomalies, The plot of the data over time is a r … - 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 sand, silt and loam will settle at diffe … - 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 for histogram, there … - 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 specification, then this is the test for you. In this case, y … - 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 certification. It is the key idea of ong … - 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 your data provide a bit mo … - 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 range of tools to analytically make t … - 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 make a difference? … - 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) studied graphical percepti … - 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 observation that became generalized as the … - 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 the experiment. Despite creatin … - 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 process is better than the old one on a … - 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, we establish a null an … - 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 data. By using a sample from a population and not meas … - 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 than some specification, then this is the test for you. Oh, you also kn … - 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. Within FTA, the AND and OR gates are just tw … - 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 being able to communicate the range of i … - 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 – just means it’s time to craft a histogram, right? There isn’t a … - 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 employers likewise are experimenting and … - 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 scatter plot, dot plot, o …

## 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.