What the sixteen factors measure
Cattell's sixteen personality factors are narrow traits such as warmth, dominance, rule-consciousness, vigilance, and abstractedness, found by factor-analysing descriptions of personality. This test administers the International Personality Item Pool's 163-item public-domain scales mirroring them, and places each factor as a percentile against 26,788 adults who answered the same items online. It is not the commercial 16PF.
Where the Big Five describes personality with five broad traits, Cattell's model keeps sixteen narrower ones — the difference between knowing someone is sociable and knowing whether that shows up as warmth, social boldness, or liveliness. Each factor runs between two ends, and neither end is the better one.
The sixteen factors
A · Warmth
Toward the warm end, you take an active interest in other people, comfort them, and make time for them. Toward the detached end, you keep more distance from other people's lives and problems.
B · Reasoning
Toward the confident self-view end, you see yourself as quick to learn, analytical, and able to hold your own in an argument. Toward the modest self-view end, you see yourself as an ordinary thinker and are slow to claim intellectual confidence.
C · Emotional Stability
Toward the steady end, you stay relaxed most of the time, are comfortable with yourself, and recover from setbacks readily. Toward the changeable end, you feel your moods swing and setbacks discourage you more.
E · Dominance
Toward the assertive end, you take charge, say what you think, and are willing to criticise or take strong measures. Toward the deferential end, you let others lead and decide, and seldom push back.
F · Liveliness
Toward the lively end, you joke around, enjoy loud crowds and big parties, and like to amuse people. Toward the serious end, you prefer quieter settings and are more serious than playful.
G · Rule-Consciousness
Toward the rule-bound end, you follow rules, respect authority, and believe laws should be enforced. Toward the rule-questioning end, you question authority and are comfortable bending or getting around rules.
H · Social Boldness
Toward the socially bold end, you start conversations, make friends easily, and do not mind being the centre of attention. Toward the shy end, you find approaching people hard and tend to stay in the background, especially with strangers.
I · Sensitivity
Toward the sensitive end, you are drawn to books, fiction, poetry, and films, and are easily moved by them. Toward the unsentimental end, you are less drawn to fiction, poetry, or performance and less often moved by them.
L · Vigilance
Toward the wary end, you suspect hidden motives and find it hard to trust or forgive. Toward the trusting end, you assume good intentions and trust what people tell you.
M · Abstractedness
Toward the imaginative end, you get lost in thought and fantasy and do unexpected, unconventional things. Toward the grounded end, you stay grounded in the practical and prefer to do things by the book.
N · Privateness
Toward the private end, you keep your thoughts and feelings to yourself and are hard to get to know. Toward the open end, you talk openly about yourself and show what you feel.
O · Apprehension
Toward the apprehensive end, you worry, dwell on past mistakes, and feel hurt or guilty easily. Toward the self-assured end, you are seldom bothered by things and let past mistakes go.
Q1 · Openness to Change
Toward the open to ideas end, you enjoy new and abstract ideas, philosophical talk, art, and variety. Toward the prefers the familiar end, you prefer concrete, familiar ground to abstract or theoretical discussion.
Q2 · Self-Reliance
Toward the self-reliant end, you prefer doing things by yourself and value quiet and privacy. Toward the group-oriented end, you enjoy teamwork and being part of a group, and miss company without it.
Q3 · Perfectionism
Toward the orderly end, you want things just right, keep order, and get chores done straight away. Toward the flexible end, you are relaxed about mess and happy to leave unpleasant tasks for later.
Q4 · Tension
Toward the irritable end, you get irritated and angry quickly and are quick to judge others. Toward the patient end, you are hard to annoy, forgive readily, and have a good word for most people.
Factor B is self-rated here
In the commercial 16PF, Factor B (Reasoning) is a short set of problems with right answers. The IPIP scale that mirrors it, Intellect, asks how bright you consider yourself — so it measures intellectual self-confidence, not ability. For reasoning itself, the reasoning test counts problems solved, without an IQ.
Why the IPIP version, and what the percentiles mean
The 16PF Fifth Edition is a commercial instrument with its own items and norms. The International Personality Item Pool publishes public-domain scales written to cover the same sixteen factors, and that is what this test administers, verbatim. Your scores are placed against 26,788 adults who answered the same 163 items online at the Open-Source Psychometrics Project (median age 24, 59% women, 48% US), so each percentile says where you sit in that group — a large reference group, not the population. There are no sten scores and no global factors: the 16PF's own equations for those were never derived for these items.
What is free and what the report adds
Your three most distinctive factors, the methodology, and the sources are free. The advanced report adds the other thirteen factors with percentiles and likely ranges, what your most distinctive factors look like day to day, the pairs of factors that usually move together but split in your profile, how this differs from Cattell's 16PF, a 90-day practice, and an AI reflection module.