Bee Vibration
8 Factor of Design for Maintainability

8 Factor of Design for Maintainability

2009-06-02 RockClimbing (2)
8 factors of design for maintainability

The first time I changed the oil filter of my car (first car in high school) I smashed my knuckles against an grimy block of metal. More than once. It may have been my lack of experience or improper tools. Or, it may have been a rather poor design

Watching the Indy 500, especially the pit stops, I quickly realized there has to be something different about…

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Reliability Testing Considerations
Considerations for Reliability Testing

Reliability testing to determine what will fail or when will failures occur is expensive. Organizations invest in the development of a product and attempt through the design process to create a product that is reliable.

The design process has many unknowns though. This includes uncertainties about materials, design margins, use environments, loads, and aging…

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Field Industry and Public Failure Data

Field Industry and Public Failure Data

Looking for failure data

Beyond understanding what will fail (failure mechanisms) we need to know when a system will fail. Both what and when information can be found in a variety of sources. Unlike the stock market where we are regularly warned that past performance does not indicate future performance, in reliability engineering past performance is the best predictor of future performance.


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Types of failure data

Types of failure data

Failure Types

The other day a student said they are asking for failure dates, not failure rates. That is a marked improvement when requesting information for the many sources of reliability information. It is not sufficient though.

Also ask for the type of failures expected or encountered during the testing or observation. (more…)

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Sources of Reliability Data

Sources of Reliability Data

Types of Reliability Data

We rely on data to make decisions, to reveal patterns or trends, to learn about our systems and world. Data has many forms and sources. Reliability data may provide what will fail and/or when a device will fail. (more…)

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Levene’s Test

Levene’s Test

2008-02-29 RockClimbing

Levene’s Test

A non-parametric test to evaluate if a set of samples have the same variance. If the variances are equal they have homogeneity of variances.

Some statistical test assume equal variances across samples, such as analysis of variance and many types of hypothesis tests. It is also assumed for statistical process control purposes to determine stability (often done with range (r chart) or…

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Contingency Coefficient
Contingency Coefficient

A contingency table, as in the chi-squared test of independence, reveals if two sets of data or groups are independent or not. It does not reveal the strength of the dependance. The contingency coefficient is a non-parametric measure of the association for cross-classification data.

After calculating the chi-squared value from the contingency table exercise, we can use…

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Upcoming CRE prep course

Upcoming CRE prep course

I’ll be teaching the CRE prep course again for the ASQ Silicon Valley Section. We’re using Adobe Connect to provide the course online and recorded.

Join us for the discussions, practice and lectures to get you back put to speed and ready for the ASQ CRE exam in October 2014.

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Boots enjoying an afternoon nap on a stump

Boots enjoying an afternoon nap on a stump

Chi-Square Test of Independence

Chi-Square Test of Independence

Χ2 Test of Independence

The chi-squared (Χ2) test provides a means to determine independence between two or more variables. In this case it works for count data.

Contingency table or row and column (r x c) analysis are other common names for this analysis. It is useful when comparing results from different treatments or processes. (more…)

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