This does not consider the likelihood that a significant number of people who are actually above average, think they are below average because of abuse or low self esteem. It does seem unreasonable to me that this could be ten percent of the population. To adjust for this, ten percent should be subtracted from the fifty percent who are "really above average" and added to the thirty percent who erroneously believe they are above average. Thus forty percent of the population may believe they are above average when they are not.