For a little more explanation… (yes, I will explain my disclaimers later)…
In Appendix A of Russell Barkley’s book, he writes, “To get a better idea of whether you fit the picture of adult ADHD, see how many of the symptoms on pages XXX-YYY represent you experiences.” And then he presents the 91 symptoms that I put in the spreadsheet. Along with each symptom, he also gives the percentage of adults with ADHD who claim the symptom, and the percentage of adults in the community who claim the symptom.
For example, the first symptom is “Find it difficult to tolerate waiting; impatient” to which 75% of ADHD adults respond positively. The second one - “Make decisions impulsively” - 79% of adults w/ ADHD responding positively. Answering yes or no to either or both of these questions does not mean you have or do not have ADHD. But about 59% (0.75 * 0.79) adults w/ ADHD will answer both positively, about 16% (0.75 * (1-0.79)) will answer just the first positively, 20% ((1-0.75) * 0.79) will answer the second, and only 0.5% will answer neither positively. We can keep combining probabilities to see what percentage of Adults w/ ADHD answer exactly as you did.
Honestly, with this many questions, the percentage is going to be really tiny. However, because we also have numbers for how “adults in the community” respond, we can also compute what percentage of those would respond exactly as you did. That will also be really tiny. But while they are both tiny, one may be far bigger than the other, which gives an indication of which group you fall into.
Say you answered only the first question positively. About 16% of adults with ADHD will answer that way. However, only about 5% of adults in the community would answer this way, meaning there is about a 76% (16 / (16 + 5)) chance you fall into the Adults w/ ADHD category and 24% (5 / (16 + 5)) chance you fit in the Adults in the Community category.
- The math is based upon the assumption that these symptoms are completely independent. Like if someone were rolling percentile dice to answer the questions, using different cutoffs depending upon which category they were in. But we know that is not really the case. Someone with a “(16) poor sense of time” probably also “(17) waste[s] or mismanages [their] time.”
- We don’t know how rigorous and applicable the percentages are for each symptom. How big of a study was it? Are the results applicable to society as a whole? … stuff like this …
- Clearly, I have not studied whether this application of the individual results is valid. I haven’t compared the computed values of the spreadsheet with any real people (well, other than me, where it indicates I fit into the Adult w/ ADHD category).
Obviously, if you don’t answer the questions honestly (or are not self-aware enough to answer them accurately), then the results aren’t valid. That is the case with all sorts of self-evaluations, which is why we go to medical professionals.
If I were to bring this to a medical professional, I would bring the whole thing, since the survey itself (and its source) would be useful. I think the final computation is interesting and likely useful (I think results for most people will fall very strongly in one category or another), but I wouldn’t expect a medical professional to trust some random person you found on the internet.