Can you trust your data?
the very first question we need to ask when we perform a
statistical analysis. If the data's no good, it doesn't matter what
statistical methods we employ, nor how much expertise we have in
analyzing data. If we start with bad data, we'll end up with
unreliable results. Garbage in, garbage out, as they
So, can you trust your data? Are you positive?... Continue Reading
We had solar panels fitted on our property in 2011. Last year,
we had a few problems with the equipment. It was shutting down at
various times throughout the day, typically when it was very sunny,
resulting in no electricity being generated.
In summer 2016, I completed a statistical analysis in Minitab to
confirm my suspicions that my solar panels were not working as well
as they did when they were... Continue Reading
In my time at Minitab, I’ve gotten a good understanding of what
types of graphs users create. Everyone knows about histograms, bar
charts, and time series plots. Even relatively less familiar plots
like the interval plot and
individual value plot are still used quite often.
However, one of the most underutilized graphs we have available is
the area graph. If you’re not familiar with an Area... Continue Reading
may not be a situation more perilous than being a character on
Game of Thrones. Warden of the North, Hand of
the King, and apparent protagonist of the entire series? Off with
your head before the end of the first season! Last male heir of a
royal bloodline? Here, have a pot of molten gold poured on your
head! Invited to a wedding? Well, you probably know what happens at
weddings in the show. ... Continue Reading
The two previous posts in this series focused on manipulating
data using Minitab’s
calculator and the
this third and final post, we continue to explore helpful features
for working with text data and will focus on some features in
Minitab’s Editor menu.
Using the Editor Menu
Editor menu is unique in that the options displayed
depend on what is currently active (worksheet, graph,... Continue Reading
Have you ever had a probability
plot that looks like this?
The probability plot above is based on patient weight (in
pounds) after surgery minus patient weight (again, in pounds)
The red line appears to go through the data, indicating a
good fit to the Normal, but there are clusters of plotting
points at the same measured value. This occurs on a probability
plot when there are many... 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’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’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. But Minitab’s enhanced data manipulation
features make it easier to work with text data, too.
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
You... Continue Reading
One of the biggest pieces of international news last year was
the so-called "Brexit" referendum, in which a majority of voters in
the United Kingdom cast their ballots to leave the European Union
outcome shocked the world. Follow-up media coverage has asserted
that the younger generation prefers to remain in the EU since that
means more opportunities on the continent. The older... Continue Reading
Easy access to the right tools makes any task easier. That
simple idea has made the Swiss Army knife essential for
adventurers: just one item in your pocket gives you instant access
to dozens of tools when you need them.
your current adventures include analyzing data, the multifaceted
Editor menu in Minitab Statistical
Software is just as essential.
Minitab’s Dynamic Editor Menu
Whether you’re... Continue Reading
It's a very exciting time at Minitab's offices around the world
because we've just announced the availability of
Minitab® 18 Statistical Software.
is everywhere today, but to use it to make sound, strategic
business decisions, you need to have tools that turn that data into
knowledge and insights. We've designed Minitab 18 to do
We've incorporated a lot of new
features, made some... Continue Reading
Before cutting an expensive piece of granite for a countertop, a
good carpenter will first confirm he has measured correctly. Acting
on faulty measurements could be costly.
no measurement system is perfect, we rely on such systems to
quantify data that help us control quality and monitor changes in
critical processes. So, how do you know whether the changes you see
are valid and not just 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
"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
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
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
In Part 1 of Gauging Gage, I looked at how adequate a
sampling of 10 parts is for a Gage R&R Study and providing
some advice based on the results.
Now I want to turn my attention to the other two factors in the
standard Gage experiment: 3 operators and 2 replicates.
Specifically, what if instead of increasing the number of parts in
the experiment (my previous post demonstrated you would need... Continue Reading
"You take 10 parts and have 3 operators measure each 2
This standard approach to a Gage R&R experiment is so
common, so accepted, so ubiquitous that few people ever question
whether it is effective. Obviously one could look at whether
3 is an adequate number of operators or 2 an adequate number of
replicates, but in this first of a series of posts about
"Gauging Gage," I want to look at... 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
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