The web lets ignorance get spread alarmingly fast. Last month the Hopkinson Report had a blog post about 8 Public Speaking Mistakes That Make You Look Like A Newbie. Their introduction made a ninth mistake - quoting statistics without checking their primary source to see whether they were right or made any sense. They showed a list of ten Top Fears which were claimed to have come from the National Institute of Mental Health (NIMH).
A Google search revealed that their list came from a web page on the Statistic Brain web site. That list was labeled Top Phobias, and is shown above including a fourth column with the percent of the U.S. population having each phobia. There is a difference between a fear and a phobia, so the Hopkinson Report seems to have mislabeled their table.
That page at the Statistic Brain site contains a box which says their source was NIMH, and data were verified on March 28, 2012. So, I went to the NIMH web site and drilled down on their Statistics web page. (Click on the tab for Prevalence, and then click on Serious Mental Illness and By Disorder). There only are results listed for two of the ten phobias - Social Phobia and Agoraphobia. NIMH list two different percentages - a lifetime prevalence and a 12-month prevalence. I’ve included both, but neither matches what was listed by Statistic Brain.
It gets much worse. For any mental disorder, NIMH lists a lifetime prevalence of 46.4% and a 12-month prevalence of 26.2%. The 74% for public speaking and 68% for death are way above 46.4%, so they are obviously bogus (presumably really fears rather than phobias).
Phobia of spiders is a subtype of specific phobia, for which NIMH lists a lifetime prevalence of 12.5% and a 12-month prevalence of 8.7%. Statistics Brain listed 30.5% for spiders, which again is too large and obviously bogus.
Phobia of public speaking is a subtype of social phobia, for which NIMH lists a lifetime prevalence of 12.1% and a 12-month prevalence of 6.8%. Statistics Brain listed 74% for public speaking, which again is way too large and thus obviously bogus. (They have another web page that lists that 74% as a fear, and also shows percentages for both men and women).
So, Statistic Brain pinned my bogometer. The takeaway from this blog post is that you always should be skeptical and go back to the primary source before you quote alarming statistics that you find on the web.
UPDATE June 17, 2014
Even If you interpret the items on their top ten list as being fears, you run into another contradiction. They list fear of public speaking first (74%) and fear of social situations sixth (7.9%). But fear of public speaking is a subtype of social fear, so it should be smaller not larger. If you look at results from the NIMH sponsored National Comorbidity Replication, you will find that 24.1% for any social fear and 21.2% for fear of public speaking/performance.
Also, Statistic Brain’s use of the term sociophobia should raise a big red flag. Psychologists don’t commonly use that term. In PubMed it appears just eight times, while the phrase “social phobia” appears 3098 times and “social anxiety” appears 3266 times.
The bogometer image was derived from this one of a digital multimeter.