# Why don't we measure things with z-scores

**URL:** <https://forum.kirupa.com/t/why-dont-we-measure-things-with-z-scores/234736>\
**Category:** random\
**Created:** [August 5, 2007, 2:12pm UTC](https://forum.kirupa.com/t/why-dont-we-measure-things-with-z-scores/234736 "2007-08-05T14:12:34Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Al6200](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Al6200](https://forum.kirupa.com/u/Al6200)\
**Post date:** [August 5, 2007, 2:12pm UTC](https://forum.kirupa.com/t/why-dont-we-measure-things-with-z-scores/234736/1 "2007-08-05T14:12:34Z")

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WARNING: IF YOU HAVE NO STATISTICS BACKGROUND THIS WILL BE UTTER GIBBERISH.

Like the SATs. The SATs are graded on a scale of 200-800, with a mean of 500 and a standard deviation of 100. So 600 is z = 1, 700 is z = 2, 800 is z = 3.

But here’s the thing, why do they even mess with the whole 200-800 number? Why don’t they just give you a z-score as what you got on the SAT.

Because with the current system, to convert SAT to IQ, you have to:

1. Take score
2. Subtract out 500
3. Divide by 100
4. Multiply by 15
5. Add 100

BUT WHY DON’T THE IQ PEOPLE EVEN JUST SAY OKAY YOUR IQ IS -1, or 1, or 2, or 3, or 4, or whatever.

Cause if they did that anyone could know what the score to any test meant, just by the Z.

[SIZE=7]So therefore, in conclusion, all standardized tests or measures should be scored by z score, with 0 being average, -1… being below average, and 1… being above average.

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