Is the Risk of an Ebola Pandemic Even Worth Worrying About?

In his post yesterday, my colleague Jim Colton applied binary logistic regression to data on the current ebola virus outbreak in Guinea, Liberia, and Sierra Leone, and revealed that, horrific as it is, this outbreak actually appears to have a lower death rate than some earlier ones. 

He didn't address the potential for a global ebola pandemic, but over the last few days more than enough leading publications have featured extremely scary headlines about this extremely remote possibility. Less reputable organizations have promulgated even more exaggerated stories, usually with some ludicrous...

How Deadly Is this Ebola Outbreak?

The current Ebola outbreak in Guinea, Liberia, and Sierra Leone is making headlines around the world, and rightfully so: it's a frightening disease, and last week the World Health Organization reported its spread is outpacing their response. Nearly 900 of  the more than 1,600 people infected during this outbreak have died, including some leading medical professionals trying to stanch the outbreak's spread. And yesterday, one of the American doctors who contracted the disease arrived back in the U.S. for treatment.

Many sources state that Ebola virus outbreaks have a case fatality rate of up to...

Chaos at the Kentucky Derby? Bet on It!

If betting wasn't allowed on horse racing, the Kentucky Derby would likely be a little-known event of interest only to a small group of horse racing enthusiasts. But like the Tour de France, the World Cup, and the Masters Tournament, even those with little or no knowledge of the sport in general seem drawn to the excitement over its premier event—the mint juleps, the hats...and of course, the betting.

As most of you probably already know, then, a big part of betting is the odds placed on a particular horse, so that a bet on the favorite to win the race would pay out significantly less than a...

Re-analyzing Wine Tastes with Minitab 17

In April 2012, I wrote a short paper on binary logistic regression to analyze wine tasting data. At that time, François Hollande was about to get elected as French president and in the U.S., Mitt Romney was winning the Republican primaries. That seems like a long time ago…

Now, in 2014, Minitab 17 Statistical Software has just been released. Had Minitab 17, been available in 2012, would have I conducted my analysis in a different way?  Would the results still look similar?  I decided to re-analyze my April 2012 data with Minitab 17 and assess the differences, if there are any.

There were no...

Unleash the Power of Linear Models with Minitab 17

We released Minitab 17 Statistical Software a couple of days ago. Certainly every new release of Minitab is a reason to celebrate. However, I am particularly excited about Minitab 17 from a data analyst’s perspective. 

If you read my blogs regularly, you’ll know that I’ve extensively used and written about linear models. Minitab 17 has a ton of new features that expand and enhance many types of linear models. I’m thrilled!

In this post, I want to share with my fellow analysts the new linear model features and the benefits that they provide.

New Linear Model Analyses in Minitab 17

We’ve added...

Revisiting the Relationship between Rushing and NFL Wins with Binary Fitted Line Plots

Back in November, I wrote about why running the football doesn’t cause you to win games in the NFL. I used binary logistic regression to look at the relationship between rush attempts (both by the lead rusher and by the team) and wins. The results showed that the model for rush attempts by the lead rusher and wins fit the data poorly. But the model for team rush attempts and wins did fit the data well (although we went on to show that the team rushing attempts wasn’t causing the winning).

We were able to conclude this by looking at the p-value and goodness-of-fit tests. But what if we wanted...

Regression Analysis Tutorial and Examples

I’ve written a number of blog posts about regression analysis and I think it’s helpful to collect them in this post to create a regression tutorial. I’ll supplement my own posts with some from my colleagues.

This tutorial covers many aspects of regression analysis including: choosing the type of regression analysis to use, specifying the model, interpreting the results, determining how well the model fits, making predictions, and checking the assumptions. At the end, I include examples of different types of regression analyses.

If you’re learning regression analysis right now, you might want to...

Correlation Is not Causation: Why Running the Football Doesn’t Cause You to Win Games in the NFL

I know we lost by 2 touchdowns, but if only you had given Peterson 3 more carries we would have won!

Last week, ESPN ran an article about why the running game still matters. They used statistics to show that the more you run the football in the NFL, the more likely you are to win the game. Specifically, if you have a running back who gets at least 20 carries, you win about 70% of the time. Statistics from different eras all had the same result: it appears that the more you run the football, the better your odds of winning the football game are.

If only it were that simple.

There is no doubt that...

Interpreting Halloween Statistics with Binary Logistic Regression

As Halloween is almost here, I'm ready to check out some Halloween statistics. You can have a lot of fun with Minitab on Halloween.

The National Retail Foundation (NRF) released the results of their Halloween Consumer Spending Survey last month. The basics are easy to summarize:

Because we have Minitab, we can dig a little deeper into the data. The NRF gives some information about the proportion of respondents who participate and the proportion of participators who will celebrate with different activities. The proportions for participators are broken down by different age groups. There’s...

How to Draft an NFL Pro-Bowl Player

The Pro Bowl is the National Football League’s version of an all-star team. In this blog post, I'll look at all the NFL draft picks from 1996 through 2008 and, using Minitab Statistical Software, model the probability of making it to at least one Pro Bowl based on draft order, the NFL team that drafted the player, the NCAA team the player came from, and the position of the player.

I did not include 2009-2013 drafts in this analysis since players drafted in 2009 and beyond haven’t had a reasonable opportunity to make the Pro Bowl. As shown in the graph below, the proportion of drafted players...

Coffee or Tea? Analyzing Categorical Data with Minitab

Here at Minitab we have a quite a few coffee drinkers.  From personal observation, it seemed as if people who are more outgoing are the ones doing most of the coffee drinking, while people who are less outgoing seem to opt for tea.  I’d noticed this over a period of time, and eventually decided to investigate.

To test out my hypothesis, I decided to pester some of my coworkers by asking them to participate in my beverage choice survey.  Given that the data I collected is categorical rather than continuous, this also seemed like a great way to showcase some of Minitab’s tools for analyzing...

Using Binary Logistic Regression to Investigate High Employee Turnover

Human resources might not be a business area where you’d typically expect to conduct a Six Sigma project. However, Jeff Parks, Lean Six Sigma master black belt, found the opportunity to apply Six Sigma to human resources while leading quality improvement efforts at a large manufacturer of aerospace engine parts.

The manufacturer was suffering from high employee attrition, or turnover, and struggled to understand why. With a DMAIC Six Sigma project, Parks set out to work with the HR department to investigate and reduce the high turnover rates.

In 2009, the manufacturer had normal attrition rates...

Giving Thanks for the Regression Menu

Juicy, butter roasted turkey.

Steaming mashed potatoes.

Tangy cranberry relish.

Delicious candied sweet potatoes.

Creamy green bean casserole.

Sweet and airy corn bread.

Silken pumpkin pie.

The traditional Thanksgiving menu has so many mouth-watering dishes on the table, you don’t know where to start.

If you savor statistics as much as food, you might feel similarly as you gaze at all of the delicious analyses on Minitab’s Regression menu:

How can you decide which regression analysis to choose? In this post, I’ll give you some bite-sized samples of each regression dish to help you decide which one to...

Predicting the U.S. Presidential Election: Evaluating Two Models (Part Two)

Yesterday, I presented a model that uses Dow Jones data to predict the winner in Presidential elections that have an incumbent. Today, I test a model that uses S&P 500 data. (Here are the data for today's blog that you can use in Minitab Statistical Software.)

Model 2: The Three Month Change in the S&P 500

The second model is presented by Sam Stovall, Chief Equity Strategist at S&P Capital IQ in his paper, “The Presidential Predictor: Stock Price Performances Have Typically Presaged Victors.” Unlike the Dow Jones study, this paper was written vaguely and presented unhelpful statistics. Also, the...

Predicting the U.S. Presidential Election: Evaluating Two Models (Part One)

You may have read about statistical models that claim to predict the outcome of the upcoming Presidential election. It’s easy to imagine that these models are complicated and contain many demographic, sociological, economic, and political factors. However, I was surprised to read in an article that two simple models supposedly generate accurate predictions.

Both of these models use stock market data. One model is based on the Dow Jones and the other on the S&P 500. Statistics are best when they are a hands-on experience, so while neither study included the data, I obtained both the stock market...

Ditching Feathered Hair and Bell-Bottoms

Do you like checking out old yearbooks for photos and to see how the appearance of you or your friends may have changed over the years? In honor of Minitab Statistical Software’s 40th Anniversary, we dug through our own past to see how the "our look"  has changed since 1972. Check out how Minitab software packaging has evolved into what we know today:

The very beginning - 1972

The first version of Minitab was distributed in 5 boxes of punched computer cards.


Minitab 5 introduced high-resolution graphics, in addition to new statistical functions.


The Minitab Student Edition, a streamlined...

Using Minitab To Weed Out Bloopers

In my last blog, we looked at how a single data entry error can cruelly sabotage your statistical analysis.

And if that doesn't scare you silly, maybe this will.

The frequency of data entry errors can be as high as 27%, even when using the conservative "double-entry" method to record each data value twice.

So what can you do? Besides make offerings to appease Ate, the ancient Greek goddess of delusion, folly, and reckless errors?

First, some old-school advice. There’s no substitute for taking a deep breath, rolling up your sleeves, and double-checking every observation in your data.

But suppose...

Analyzing Titanic Survival Rates, Part II: Binary Logistic Regression

In honor of the 100th anniversary of the sinking of the Titanic, we recently posted a dataset on the passengers aboard the ship that included Class (coach or first), Gender (female or male), Age, and Status (survived or died).  From Age an additional column was created indicating Child (17 years or younger) or Adult (18 years or older).

In an earlier post, we showed how survival rates could be compared between levels of one variable—for example, females versus males—using Stat > Tables > Cross Tabulation and Chi Square.  But what if we wanted to take allfactors into consideration to paint a...

The Odds of Finding a Four-Leaf Clover

St. Patrick’s Day is just around the corner, and maybe you’ve found yourself thinking about four-leaf clovers and trying to find one yourself. According to Irish tradition, those who find a four-leaf clover are destined for good luck, as each leaf in the clover symbolizes good omens for faith, hope, love, and luck for the finder.

A lesser-known fact about four-leaf clovers is that they aren’t the luckiest symbol after all. Irish legend indicates that those who find a five-leaf clover will actually have more luck and financial success than those who just find a four-leaf clover.

However, good...