The 1949 film A Connecticut Yankee in King Arthur's
Court includes the song “Busy Doing Nothing,” and this
could be written about the
Null Hypothesis as it is used in statistical
The words to the song go:
We're busy doin' nothin'Workin' the whole day through
Tryin' to find lots of things not to do
And that summarises the role of
the Null Hypothesis perfectly. Let me explain why.
What's... Continue Reading
Rare events inherently occur in all kinds of
processes. In hospitals, there are medication errors, infections,
patient falls, ventilator-associated pneumonias, and other rare,
adverse events that cause prolonged hospital stays and increase
But rare events happen in many
other contexts, too. Software developers may need to track errors
in lines of programming code, or a quality... Continue Reading
For the majority of my career, I've
had the opportunity to speak at conferences and other events
somewhat regularly. I thought some of my talks were pretty good,
and some were not so good (based on ratings, my audiences didn't
always agree with either—but that's a topic for another post). But
I would guess that well over 90% of the time, my proposals were
accepted to be presented at the... Continue Reading
Users often contact Minitab technical support to ask how the
software calculates the control limits on control charts.
A frequently asked question is how the control limits are
calculated on an
I-MR Chart or Individuals Chart. If Minitab plots the upper and
lower control limits (UCL and LCL) three standard deviations above
and below the mean, why are the limits plotted at values other than
3 times... Continue Reading
As a member of Minitab's
Technical Support team, I get the opportunity to work with many
people creating control charts. They know the importance of
monitoring their processes with control charts, but many don’t
realize that they themselves could play a vital role in improving
the effectiveness of the control charts.
In this post I will show you how
to take control of your charts by using Minitab...Continue Reading
One of the most memorable presentations at the inaugural Minitab
Insights conference reminded me that data analysis and quality
improvement methods aren't only useful in our work and businesses:
they can make our home life better, too.
presenter, a continuous improvement training program manager at an
aviation company in the midwestern United States, told attendees
how he used Minitab... Continue Reading
One highlight of writing for and editing the Minitab Blog is the
opportunity to read your responses and answer your questions.
Sometimes, to my chagrin, you point out that we've made a mistake.
However, I'm particularly grateful for those comments, because it
permits us to correct inadvertent errors.
feared I had an opportunity to fix just such an error when I saw
this comment appear on one of... Continue Reading
"Data! Data! Data! I can't make bricks without clay."
— Sherlock Holmes, in Arthur Conan Doyle's The Adventure
of the Copper Beeches
Whether you're the world's greatest detective trying to crack a
case or a person trying to solve a problem at work, you're going to
need information. Facts. Data, as Sherlock Holmes
But not all data is created equal, especially if you plan to
analyze as part of... Continue Reading
As someone who has collected and analyzed real data for a
living, the idea of using simulated data for a Monte Carlo
simulation sounds a bit odd. How can you improve a real product
with simulated data? In this post, I’ll help you understand the
methods behind Monte Carlo simulation and walk you through a
simulation example using Companion by Minitab.
Companion by Minitab is a software platform that... Continue Reading
Choosing the right type of subgroup in a control chart is
crucial. In a rational subgroup, the variability within a subgroup
should encompass common causes, random, short-term variability and
represent “normal,” “typical,” natural process variations, whereas
differences between subgroups are useful to detect drifts in
variability over time (due to “special” or “assignable” causes).
Variation within... Continue Reading
you ever tried to install ventilated shelving in a closet?
You know: the heavy-duty, white- or gray-colored vinyl-coated wire
shelving? The one that allows you to get organized, more efficient
with space, and is strong and maintenance-free? Yep, that’s the
one. Did I mention this stuff is strong? As in,
really hard to cut?
It seems like a simple 4-step project. Measure the closet, go
the... Continue Reading
shopping. For some, it's the most dreaded household activity. For
others, it's fun, or perhaps just a “necessary evil.”
Personally, I enjoy it! My co-worker, Ginger, a content manager
here at Minitab, opened my eyes to something that made me love
grocery shopping even more: she shared the data behind her family’s
shopping trips. Being something of a data nerd, I really geeked out
over the... Continue Reading
you regularly perform regression analysis, you know that
R2 is a statistic used to evaluate the fit of your
model. You may even know the standard definition of R2:
the percentage of variation in the response that is explained
by the model.
Fair enough. With Minitab Statistical Software doing all the heavy
lifting to calculate your R2 values, that may be all you
ever need to know.
But if you’re... Continue Reading
Parts 1 and
2 of Gauging Gage we looked at the numbers of parts, operators,
and replicates used in a Gage R&R Study and how accurately we
could estimate %Contribution based on the choice for each. In
doing so, I hoped to provide you with valuable and interesting
information, but mostly I hoped to make you like me. I mean
like me so much that if I told you that you were doing... Continue Reading
Earlier, I wrote about the
different types of data statisticians typically encounter. In
this post, we're going to look at why, when given a choice in the
matter, we prefer to analyze continuous data rather than
categorical/attribute or discrete data.
As a reminder, when we assign something to a group or give it a
name, we have created attribute or
categorical data. If we count something,
like... Continue Reading
You run a capability analysis
and your Cpk is bad. Now what?
First, let’s start by defining
what “bad” is. In simple terms, the smaller the Cpk, the more
defects you have. So the larger your Cpk is, the
practitioners use a Cpk of 1.33 as the gold standard, so we’ll
treat that as the gold standard here, too.
Suppose we collect some data and run a capability analysis using
by Kevin Clay, guest blogger
In transactional or service processes, we often deal with
lead-time data, and usually that data does not follow the normal
Consider a Lean Six Sigma project to reduce the lead time
required to install an information technology solution at a
customer site. It should take no more than 30 days—working 10 hours
per day Monday–Friday—to complete, test and... Continue Reading
Everyone who analyzes data regularly has the experience of
getting a worksheet that just isn't ready to use. Previously I
wrote about tools you can use to
clean up and eliminate clutter in your data and
reorganize your data.
In this post, I'm going to
highlight tools that help you get the most out of messy data by
altering its characteristics.
Know Your Options
Many problems with data don't become... Continue Reading
In Part 1 of this blog series, I
compared Six Sigma to a diamond because both are valuable, have
many facets and have withstood the test of time. I also explained
how the term “Six Sigma” can be used to summarize a variety of
concepts, including philosophy, tools, methodology, or metrics. In
this post, I’ll explain short/long-term variation and
between/within-subgroup variation and how they help... Continue Reading
You've collected a bunch of
data. It wasn't easy, but you did it. Yep, there it is, right
there...just look at all those numbers, right there in neat columns
and rows. Congratulations.
I hate to ask...but what are you
going to do with your data?
If you're not sure precisely
what to do with the data you've got, graphing it is a
great way to get some valuable insight and direction. And a good
graph to... Continue Reading
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