Articles tagged Lognormal Distribution

Lognormal Distribution, Concepts and Applications

We are happy to release this video on Lognormal Distribution which is a popular distribution to model failures of non-repairable items. In this video, Hemant Urdhwareshe has explained basic concepts of lognormal distribution and its application examples. Hemant also explains its mathematical relationships to calculate MTTF, standard deviation and other parameters In addition, in the video, Hemant has illustrated how to use Minitab and Excel to visualise Lognormal Distribution. Hemant is a Fellow of ASQ and is ASQ CRE, CMBB, CSSBB, CQE and CMQ/OE. We are sure that viewers will find it useful.

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by Fred Schenkelberg Leave a Comment

Use Lognormal Distribution

The lognormal distribution has two parameters, μ and σ. These are not the same as mean and standard deviation, which is the subject of another post, yet they describe the distribution, including the reliability function.

$$ \displaystyle R(t)=1-\Phi \left( \frac{\ln (t)-\mu }{\sigma } \right)$$

Where Φ is the standard normal cumulative distribution function, and t is time. [Read more…]

by Dennis Craggs Leave a Comment

Lognormal Probability Plots

Introduction

In general, a statistical analysis of univariate data starts with a histogram. If the histogram doesn’t show a bell shape, the data probably does not follow a normal distribution. If the logarithm of the data plots as a normal histogram, then the data is lognormally distributed. Any statistical projections and parameter estimates are based on the normal distribution of the log of the data. This article focuses on the lognormal distribution and the lognormal probability plot.

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by Fred Schenkelberg 1 Comment

The 2 Parameter Lognormal Distribution 7 Formulas

This is part of a short series on the common life data distributions.

The Lognormal distribution is a versatile and continuous distribution. It is similar to the Weibull in flexibility with just slightly fatter tails in most circumstances. It is commonly used to describe time to repair behavior. This short article focuses on 7 formulas of the Lognormal Distribution.

If you want to know more about fitting a set of data to a distribution, well that is in another article.

It has the essential formulas that you may find useful when answering specific questions. Knowing a distribution’s set of parameters does provide, along with the right formulas, a quick means to answer a wide range of reliability related questions. [Read more…]

by Fred Schenkelberg 17 Comments

Calculating Lognormal Distribution Parameters

The lognormal distribution has two parameters, μ, and σ. These are not the same as mean and standard deviation, which is the subject of another post, yet they do describe the distribution, including the reliability function. [Read more…]