Assessment Statistics
Key data points that help put intelligence, personality, mental health, neurodiversity, relationships, and learning results into context.
Statistics
Numbers help, but only with context
Statistics are useful when they help users understand a result in proportion. They can show how common a pattern is, how stable a trait tends to be, or how a construct behaves across a population.
They are less useful when treated as personal prediction. Every number on this page should be read as a broad research context, not as a conclusion about one person.
Cognition and intelligence
Common cognitive context points
100
Average IQ by definition
Standard IQ scales are centered around 100 with a common standard deviation of 15.
85-115
Common average range
Many IQ scales place roughly two-thirds of scores in this broad range.
4 +/- 1
Working memory chunks
A commonly cited estimate for active working memory capacity in simple conditions.
Context
Age patterns vary
Fluid reasoning, processing speed, and knowledge do not all follow the same age pattern.
Human assessment domains
Selected population-level patterns
Personality
Personality traits tend to be moderately stable while still changing across adulthood and life context.
- Big Five traits show both heritable and environmental influence.
- Conscientiousness is commonly linked to academic and work outcomes.
- Trait interpretation should account for culture and situation.
Mental health
Mental health prevalence statistics vary by source, country, year, age group, and measurement method.
- Screeners estimate symptom burden, not diagnosis.
- Global numbers should be read with source and year attached.
- Professional help is important when symptoms cause distress or impairment.
Neurodiversity
Autism, ADHD, dyslexia, and related traits are increasingly understood dimensionally.
- Prevalence estimates vary as diagnostic criteria and awareness change.
- Adult recognition has increased in many countries.
- Self-screening can support awareness but cannot confirm diagnosis.
Relationships
Attachment and communication patterns are associated with relationship satisfaction, safety, and conflict handling.
- Attachment categories are simplifications of underlying dimensions.
- Relationship patterns can shift over time.
- Context and partner dynamics matter.
Learning
Study and learning research strongly supports active recall, spacing, feedback, and deliberate practice.
- Spaced practice beats cramming for long-term retention.
- Testing yourself supports memory more than rereading alone.
- Learning style preferences should not be overused as fixed labels.
Use with care
Why the page avoids false precision
Statistics in psychology and public health can change as measurement methods, diagnostic criteria, and population samples change. For that reason, this page focuses on stable context and links users back to sources rather than pretending every number is timeless.
For medical, psychological, educational, or employment decisions, population statistics should be interpreted by qualified professionals in the right context.
FAQ
Statistics questions
Do statistics predict my result?
No. Statistics describe groups and tendencies. Your individual context, history, environment, and current situation still matter.
How often should statistics be updated?
Statistics should be reviewed when new large-scale studies, public health updates, or framework changes become available.
Why do different sources give different prevalence rates?
Estimates vary because studies use different populations, definitions, years, sampling methods, and measurement tools.
Where can I check the sources?
Use Our Sources and source links on individual assessment pages.
Numbers are useful when they stay honest
Continue to the research page for the broader scientific context behind the statistics.
Read Research