I read “Good to Great” and “Built to Last” some years ago because they were bestsellers and had good reviews. Although I did enjoy reading them, a voice in my head kept asking questions regarding the reliability of the research and findings. After reading “The Halo Effect”, I was relieved and happy to learn that I am not the only person asking these questions.

The world of business is complicated, uncertain and unpredictable. A company’s performance depends upon a variety of factors beyond the actions of its managers. These include currency shifts, competitors’ actions, shifts in consumer preferences, technological advances, etc. The first delusion is the Halo Effect, the tendency to look at a company’s overall performance and make attributions about its culture, leadership, values, and more. Our thinking is prejudiced by financial performance. In good times, companies are praised and their success is attributed to a variety of internal factors. In bad times, companies are criticized and these factors, which may not have changed, are attributed for the failures. The reality is more complicated and dependent upon uncertain and unpredictable factors.

An interesting section of this book is the one on the delusion of absolute performance. Company performance is relative, not absolute. A company can improve and fall further behind its rivals at the same time. For instance, GM today produces cars with better quality and more features than in the past. But its loss in market share is owed to a myriad of factors, including Asian competitors.

This is an excellent book because it will make you THINK. Is an oil company great if its profits soared when oil prices went up? Can the formulas used by successful companies in the 80s or 90s be applied to guarantee success today? A professor once told me that to predict future performance by analyzing past data is like driving a car forward while looking at the rear view mirror. In the appendix of this book there are tables showing the performance of the companies studied in “In Search of Excellence” and “Built to Last”. It is interesting to note the difference in performance in the years before and after these studies.

The author, Phil Rosenzweig, is a professor at IMD in Switzerland and former Harvard Business School professor. He wrote this book to stimulate discussion and help managers become wiser – “more discerning, more appropriately skeptical, and less vulnerable to simplistic formulas and quick fix remedies.” In my case, this book has given me a new perspective on business books.

The following is a brief summary of the nine delusions:

1. Halo Effect: Tendency to look at a company’s overall performance and make attributions about its culture, leadership, values, and more.

2. Correlation and Causality: Two things may be correlated, but we may not know which one causes which.

3. Single Explanations: Many studies show that a particular factor leads to improved performance. But since many of these factors are highly correlated, the effect of each one is usually less than suggested.

4. Connecting the Winning Dots: If we pick a number of successful companies and search for what they have in common, we’ll never isolate the reasons for their success, because we have no way of comparing them with less successful companies.

5. Rigorous Research: If the data aren’t of good quality, the data size and research methodology don’t matter.

6. Lasting Success: Almost all high-performing companies regress over time. The promise of a blueprint for lasting success is attractive but unrealistic.

7. Absolute Performance: Company performance is relative, not absolute. A company can improve and fall further behind its rivals at the same time.

8. The Wrong End of the Stick: It may be true that successful companies often pursued highly focused strategies, but highly focused strategies do not necessarily lead to success.

9. Organizational Physics: Company performance doesn’t obey immutable laws of nature and can’t be predicted with the accuracy of science – despite our desire for certainty and order.

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