Really surprisingly, given all the buzz about this study over the years since it was published, nobody has been able to reproduce it. Tim Hartford covers the topic in his new book, The Data Detective. The many reproductions have demonstrated that, on average, the described effect does not exist. It is of course disappointing that studies disproving a popular theory have such difficulty getting published and are never given the same attention.


Drawing by Peter FitzGerald

Vaccinations are just like seatbelts

As heated debates go, mandatory Covid-19 vaccination discussions often seem to require fire extinguishers. I have been listening to a lot of such discussions on the radio and in podcasts, and watching politicians dancing around the question on TV. I have been surprised how reluctant everyone has been to take the position that vaccinations should be mandatory. I just don’t get it. I hope some readers will straighten me out. Let me outline what I have heard and what I think about the question.

These three arguments are the most common ones I have heard here in Switzerland and while…


19th in a deep and intense series on the Net Promoter Score (NPS) and System. You can find the other articles in the series here. This article is about a tricky subject: calculating how much your customers are worth to you.

While you can find many methods of doing the calculation on the web, there is only one correct answer. The value of a customer to your company is the total cash flow they generate for you over their entire lifetime. The single calculation method for this is Discounted Cash Flow; the Net Present Value of all cash flows out…


This is the 18th article in a series on the Net Promoter Score and Net Promoter System. The subject this time is a critical one: the relationship between NPS trends and revenue. The topic has been somewhat controversial over the years, though I am not entirely sure why.

If you work for a for-profit organization, every activity should contribute to your operating profit. If you personally have no credible background in finance, your company Chief Financial Officer is critical to your success. …


This is the 17th article in a series on the Net Promoter Score and Net Promoter System. This time I cover cultural differences in the way people respond to surveys.

As a person who has lived and worked in seven countries, I believe cultural differences exist and matter. My career has taken me regularly to countries in Africa, Asia, Europe and North America and I have directly observed that people behave differently, especially in business situations. A lot has been written on the subject. My favorite book on the subject is When Cultures Collide by Richard D. Lewis [1]. Cultures…


This is the 16th article in a series on the Net Promoter Score and Net Promoter System. You can find the entire series here.

In addition to the direct marketing techniques mentioned in my last article, here are some additional ways of improving response rates to email-based surveys, in priority sequence:

  1. By far the most important thing you can do is allow respondents to respond to the survey directly in the email they receive. Unfortunately, this is technically difficult. The best you can do is to embed the first question in the email, usually the overall rating question. Use HTML…

This is the 15th article in a series on the Net Promoter Score and Net Promoter System. The subject this time is the use of classical direct marketing techniques to improve response rates. By classical, well… yes, I do mean ‘old’.

Like most people, I receive lots of survey requests by email. Unlike most people, I don’t just delete them all. I want to learn. What I usually learn is that most survey designers don’t understand even the most basic direct marketing techniques. Here are some that you may want to consider.

My direct marketing guru is Drayton Bird, author…


Welcome to the 14th article in my series about NPS and the Net Promoter System. (You can find earlier articles here.) This time I cover response rates, sample sizes and statistical significance. Perhaps the most important points are about how to communicate such technical concepts. (Hint: Don’t!)

All survey types are sensitive to response rates. The lower your response rate, the less accurate your survey. Bain analysis shows that surveys with low response rates give over-optimistic results, as the people who like you tend to respond more easily than those who do not. Getting high response rates is primarily a…


The simple logic used to argue that Glyphosate / Roundup should be banned in Austria is its presence on the IARC list of substances that are “probably carcinogenic.” So the next obvious step is also simple: Pure logic dictates that similar laws should be passed to ban everything else that is on the same list. Here are some examples of what that means:

  • Red meat.
  • Domestic heating wood.
  • Shift work that disturbs circadian rhythms.
  • Being a hairdresser or barber. (Yes, these professions are explicitly on the list.)
  • Petroleum refining as an occupation.
  • Cured meat, cured fish, and beer, as they…


This is the 13th episode in my series on the Net Promoter Score and the Net Promoter System. This one is a bit longer than the average and covers some important topics, including whether you should bother surveying your customers at all. If you have missed some prior articles in the series you will find them on our blog page here.

The first step in designing surveys is being selective about what research you are going to do. Make sure you are going to provide customers with more value than you will extract from them.

Here are some considerations that…

Maurice FitzGerald

Author. Retired VP of Customer Experience for HP’s $4B software division. 7-country career at HP, Compaq, DEC, Wrangler. Passionate about science and nutrition.

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