I requested the book. I opened it to the first page. Here's the opening:
How many college-level individuals procrastinate? Often? Seriously? No one seems to know. Incredibly, this important question has not inspired many factual studies. Our guess? About ninety-five percent. (Ellis and Knaus 1)So it's just a guess? And this thirty-year-old guess is still being cited? The authors aren't even researchers; they're psychotherapists. Which is not to say they don't know what they're talking about, but rather to ask why on earth serious researchers keep citing them instead of doing some actual research on the numbers. I wonder if some of the citations were borrowed from other sources without checking the original source. It's not a scholarly source. It's a self-help book.
Ellis, Albert, and William J. Knaus. Overcoming Procrastination, or How to Think and Act Rationally in Spite of Life's Inevitable Hassles. New York: Institute for Rational Living, 1977.