Which of the following is true of the prevalence of intellectual disability (ID)?
A) Since a person's IQ is stable, someone diagnosed with ID in childhood always continues to qualify for a diagnosis later in life.
B) The prevalence of ID is 2.2% because that is the percentage of individuals who fall 2 standard deviations below the mean on the normal curve of IQ scores.
C) Screening adults for ID results in a much lower prevalence rate than screening school-age children.
D) ID occurs in equal rates in males and females.

Question

Quizplus · Accepted Answer

Screening adults for ID results in a much lower prevalence rate than screening school-age children because many individuals with mild or moderate ID may have developed coping skills and strategies that enable them to function well in society, making them less likely to be identified through screening methods. As a result, adult diagnoses of ID are often based on a history of intellectual impairment during childhood or early adolescence rather than on current IQ scores.

Answer: B 
 The prevalence of ID is often estimated based on the percentage of individuals who fall 2 standard deviations below the mean on the normal curve of IQ scores, which is approximately 2.2% of the population. However, this method of estimation may not capture all individuals with ID, particularly those with mild or moderate impairment who may fall above this cutoff but still experience significant difficulties in daily life.

Therefore, while B is technically correct, C provides more complete information about the limitations of prevalence estimates based on IQ scores. Answers A and D are incorrect because they suggest that ID is a static condition that remains constant over time and is equally likely to occur in males and females, respectively. These assertions are not supported by research on ID.

Which of the Following Is True of the Prevalence of Intellectual