IQ score ranges

The same raw correct count can map to different IQ numbers at different ages.

[Raw score] → [Age band] → [Scaled IQ]
                 → [Label on a chart]

Why age changes the number

Standardized scores answer a relative question: how did this person do beside peers. Peers are usually people of a similar age in the norm sample.

A child who solves twenty items and an adult who solves twenty items are not automatically tied. Each is compared with their own age table in the manual.

That is why a birthday can move a scaled score even when the answer sheet did not change. The chart below uses a common Wechsler-style layout with a mean of 100 and a standard deviation of 15.

The percentages are estimates of how many people fall in each band on a normal curve. They are not a headcount of any one country, and they are not a medical finding about a reader.

Bands on an SD 15 scale

Above 130 is about 2.2 percent of the reference curve. Some societies use a cutoff near here. The label very superior is a test-manual phrase, not a diagnosis. From 120 to 129 is about 6.7 percent. Manuals often call this superior. It is still a band on one scale.

From 110 to 119 is about 16.1 percent. This is above the middle of the curve and below the superior band. From 90 to 109 is about 50 percent. This is the large middle. Most people in the norm sample land here.

From 80 to 89 is about 16.1 percent. The usual manual phrase is below average. It is not a school placement by itself. From 70 to 79 is about 6.7 percent. Manuals may say borderline. A single number in this band is not a clinical decision.

Below 70 is about 2.2 percent on the ideal curve. The phrase intellectual disability belongs to a clinical evaluation with more than one score. A chart does not assign it to a person reading an article.

  IQ
 130| ██  ~2.2%
 120| ████ ~6.7%
 110| ██████ ~16%
 100| ████████ ~50% in 90-109
  80| ██████ ~16%
  70| ████ ~6.7%
   0| ██  ~2.2% below 70

Using the bands without mislabeling people

Start with the mean. On the scale in this article the middle is 100. Half the model sits above it and half sits below it, but the pile is thickest in the center.

The 90 to 109 band holds about half the reference curve because the curve is tall there. Being inside it is the ordinary outcome of a normed test.

Moving fifteen points is one standard deviation. The share of people drops as you walk away from 100 in either direction.

The shares 16.1, 6.7, and 2.2 are rounded pictures of that drop. A real norm sample wiggles around those ideals.

Do not add the percentages until they equal 100 in your head and then scold a country. Sampling, age, and edition move the edges.

A score of 110 and a score of 119 share a band and can still feel different on a hard subtest. Bands are bins, not clones.

The superior band from 120 to 129 is uncommon and still not rare in a large city. A school can hold several people there without being a special planet.

The band above 130 is about two in a hundred on the ideal curve. Societies that recruit near this line are selecting a tail, not defining the word intelligence for everyone else.

Labels such as borderline are manual shorthand. They were written for examiners who also see confidence intervals, behavior, and history.

A confidence interval is the range the manual allows around the point score. A single sitting is not a needle with infinite precision.

If the interval crosses from 80 into the 90s, the honest report says the band is uncertain. Articles that print only the point score skip that humility.

Below 70 on a chart is a statistical tail. A clinical term for disability requires more evidence than a blog table, including adaptive skills in daily life.

Age matters again here. A raw performance that is typical at one age can scale differently a year later because the comparison group changed.

Different publishers do not promise identical numbers. A 112 on one battery and a 106 on another can both be careful work.

Screening tools used in a classroom are shorter. They estimate. They are not a full WAIS sitting and should not be narrated as one.

When you cite a band, cite the scale family beside it. SD 15 and SD 16 charts look alike and still shift the tails.

Trio rounds do not land in these bins. If a friend asks which band a treasure time belongs to, the accurate answer is none.

Keep the chart as a legend for published scores. Keep the game as a place to practice a card rule.

Trio IQ in this story

Trio IQ never converts a round into one of these bands. A fast treasure round and a slow one are game results. They are not entries on a Wechsler table.

Takeaway

[Read the rule] → [Try one example] → [Play one round]

Step	Do this
Name the idea	Say it in one sentence before you trust a chart.
Check the source	Prefer a published test manual over a nameless quiz.
Practice a rule	Open Play and use the rule on cards.