Blog posts and articles about using Minitab software in quality improvement projects, research, and more.

In 1898, Russian economist Ladislaus Bortkiewicz published his
first statistics book entitled Das Gesetz der keinem
Zahlen, in which he included an example that
eventually became famous for illustrating the Poisson distribution.
Bortkiewicz researched
the annual deaths by horse kicks in the Prussian Army from
1875-1984. Data was recorded from 14 different army corps, with one
being the Guard... Continue Reading

The
Cp and Cpk are well known capability indices commonly
used to ensure that a process spread is as small as possible
compared to the tolerance interval (Cp), or that it stays well
within specifications (Cpk).
Yet another type of capability index exists: the Cpm, which is
much less known and used less frequently. The main difference
between the Cpm and the other capability indices is that the... Continue Reading

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The two previous posts in this series focused on manipulating
data using Minitab’s
calculator and the
Data menu.
In
this third and final post, we continue to explore helpful features
for working with text data and will focus on some new features in
Minitab 17.2’s Editor menu.
Using the Editor Menu
The Editor menu is unique in that the options displayed depend
on what is currently active... Continue Reading

My previous post focused on
manipulating text data using Minitab’s calculator.
In this post we continue to explore some of the useful tools for
working with text data, and here we’ll focus on Minitab 17.2’s Data
menu. This is the second in a 3-part series, and in the final post
we’ll look at the new features in Minitab 17.2’s Editor
menu.
Using the Data Menu
When I think of the Data menu, I think... Continue Reading

With Minitab, it’s easy to create graphs and manage numeric,
date/time and text data. Now Minitab 17.2’s enhanced data
manipulation features make it even easier to work with text
data.
This
is the first of three posts in which I'm going to focus on various
tools in Minitab that are useful when working with text data,
including the Calculator, the Data menu, and the Editor menu.
Using the Calculator
Y... Continue Reading

As a member of Minitab's Technical Support team, I get the
opportunity to work with many people using DOE (Design of
Experiments).
People often will call after they've already chosen their
design, run the experiment, and
identified the important factors in their process. But
now what? They have to find the best settings, but with
several factors and responses, what should they do?
"I wish I had
a... Continue Reading

In this series of posts, I show how hypothesis tests and
confidence intervals work by focusing on concepts and graphs rather
than equations and numbers.
Previously, I used graphs to show what statistical significance really
means. In this post, I’ll explain both confidence intervals and
confidence levels, and how they’re closely related to P values and
significance levels.
How to Correctly... Continue Reading

Minitab 17.2 is available. You can check out all of the new
stuff on the What’s New
Page, but I would say that a little demonstration is in order.
Here are some new shortcuts that make arranging your data easier in
Minitab 17.2.
Sorting
Let’s suppose that you had copied some Human Development Index data into
Minitab and wanted to sort countries in the order of their rank. In
the past, you would have... Continue Reading

To choose the
right statistical analysis, you need to know the distribution of
your data. Suppose you want to assess the capability of your
process. If you conduct an analysis that assumes the data follow a
normal distribution when, in fact, the data are nonnormal, your
results will be inaccurate. To avoid this costly error, you must
determine the distribution of your data.
So, how do you determine... Continue Reading

Imagine that you are watching a race and that you are located
close to the finish line. When the first and fastest runners
complete the race, the differences in times between them will
probably be quite small.
Now wait until the last runners arrive and consider their
finishing times. For these slowest runners, the differences in
completion times will be extremely large. This is due to the fact
that... Continue Reading

by Lion "Ari" Ondiappan Arivazhagan, guest blogger.
Predicting project completion times is one of the major
challenges project managers face. Project schedule overruns are
quite common due to the high uncertainty in estimating the amount
of time activities require, a lack of historical data
about project
completion, organizational culture, inadequate skills, the complex
and elaborative nature of... Continue Reading

This is a companion post for a series of blog posts about
understanding hypothesis tests. In this series, I create a
graphical equivalent to a 1-sample t-test and confidence interval
to help you understand how it works more intuitively.
This post focuses entirely on the steps required to create the
graphs. It’s a fairly technical and task-oriented post designed for
those who need to create the... Continue Reading

I always knew I was different. Even as a kid.
“Is that me? Way out there in left field?” I asked the doc.
“Yes,” he nodded, as he looked at my chart. “I used brushing to
identify you on the graph.”
I wasn’t sure I liked getting brushed. It felt like my true
identify was being detected and displayed in a window for all to
see.
The doctor must have sensed my discomfort.
“It’s not uncommon—even for those... Continue Reading

Monte Carlo simulation has all kinds of
useful manufacturing applications. And - in celebration of
Pi Day - I thought it would be
apropos to show how you can even use Monte Carlo simulation to
estimate pi, which of course is the mathematical constant that
represents the ratio of a circle’s circumference to its diameter.
For our example, let’s start with a circle of radius 1 inscribed
within a... Continue Reading

What do significance levels and P values mean in hypothesis
tests? What is statistical significance anyway? In this
post, I’ll continue to focus on concepts and graphs to help you
gain a more intuitive understanding of how hypothesis tests work in
statistics.
To bring it to life, I’ll add the significance level and P value
to the graph in my previous post in order to perform a graphical
version of... Continue Reading

We’ve been pretty excited about March Madness here at Minitab.
Kevin Rudy’s been busy creating his regression model and
predicting the winners for the 2015 NCAA Men’s Basketball
Tournament. But we’re not the only ones. Lots of folks are
doing their best analysis to help you plan out your bracket now
that the tip-offs for the round of 64 are just a day away. As you
ponder your last-minute changes,... Continue Reading

Our vacation planning has begun. My daughter has requested a
trip to Disney World as her high school graduation present.
For most people, trip planning might mean a simple phone call to
the local travel agent or an even simpler do-it-yourself online
booking.
Not for me.
As a statistician, a request like this means I’ve got a lot of
data analysis ahead. So many travel questions require (in my... Continue Reading

Are you ready for some madness? Me too! So let’s break down the
brackets. I’ll be using the Sagarin
Predictor ratings to determine the probability each team has of
advancing using a binary logistic model created with Minitab Statistical
Software. You can find the details of how the probabilities are
being calculated
here.
Before we start, I’d also like to mention one other set of
basketball... Continue Reading

The
NCAA Tournament is right around the corner, and you know what that
means: It’s time to start thinking about how you’re going to fill
out your bracket! For the last two years I’ve used the Sagarin
Predictor Ratings to predict the tournament. However, there is
a problem with that strategy this year. The old method uses a
regression model that calculates the probability one team has
of beating... Continue Reading

Welcome to the Hypothesis Test Casino! The featured game of the
house is roulette. But this is no ordinary game of
roulette. This is p-value roulette!
Here’s how it works: We have two roulette wheels, the Null wheel
and the Alternative wheel. Each wheel has 20 slots (instead of the
usual 37 or 38). You get to bet on one slot.
What happens if the ball lands in the slot you bet on? Well,
that depends... Continue Reading