Minitab 16 – statistics for infrequent users

Submitted by Hugo_Minney on Sun, 07/04/2010 - 22:50

It isn’t often that I write a piece which blatantly advertises a product. But a friend had to get his Masters dissertation in on time, and was fighting with the University-issued stats package, so I turned to my favourite Statistical Analysis software.
It’s my favourite because:

It does all of the statistical functions I need, in a clear and sensible way (yes you can do them in MS Excel but you have to jump through hoops)
It does Run Charts and Quality Management out of the box (you have to buy additional modules for SAS, SPSS, etc)
It’s low cost/ low maintenance (It is designed for working people rather than academics – I’m a working person with academic pretensions)
It has a really good help system

I’ve been using Minitab (www.minitab.com) for years, but I was still stunned to see this new feature – Assistant.Minitab Assistant Drop-down menu
 
 
 
 
Plot the Dots
(to quote Davis Balastracci)
When I click the Graphical Analysis button, it opens up a flow chart. This looks like a useful help screen, but it turns out that it’s live – it looks at your data for you! Of course you can plot graphs in Excel, but do you know which graphs to plot? 
Test your hypothesis
This is where the rubber meets the road. What am I trying to test, and am I right? I mean, look at the choices:

Compare one sample with a target
Compare two samples with each other
Compare more than two samples
Testing a hypothesis - the decision-tree in Minitab

ANOVA (Analysis of Variance) for continuous variables, and Chi-Square for discreet groups (male/female, ethnic group, etc) are my favourites.
It does reveal its working roots – I found that I had to use Chi-Square % Defective to test whether the balance of experienced/new staff differed between the company subdivisions (so if you are experienced, you are defective – actually that could be right?).
Looking at the results
But the way it presents the results had me excited! As an infrequent user, I get to stare at the Probability, F ratios, T ratios and everything else and think “is bigger better, or is it smaller that is better?”
Here’s what look like a set of dots where the human eye would say “OK I can see the trend, but it isn’t very close”Presenting the results of a regression line in Minitab
Minitab tells you (from the Assistant) not just the Probability that there is a relationship (nice bar chart with “degrees of blueness”), but also that in spite of the high probability of a relationship it only represents 26% of the variation (degrees of greenness) and shows the correlation too. All on a single sheet.
Go and download your own trial copy: www.mintab.com (yes, Quality Companion is about service improvement and lean – that’s worth downloading too) 

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