Standardised scores...anyone know anyhting about them?

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DD has been given standardised scores which are, supposedly, a helpful tool.

It says 100 is the national average score.
85 is below average.
115 is above average.

Am I missing somehting? Surely 101 is above average and 99 is below?

That's probably the point they have chosen to trigger help or identify more able children.
In my school 95-100 is monitored, 90-95 is targeted support with the resources in class and under 90 is specific interventions and funded time in and out of class as necessary.
We don't count more able until they are 132+ and they are supported in class.

Oh I see. That makes sense.

It says 85 or below needs 'careful consideration' and 115 or above will trigger 'tracking to ensure your DD is being siufficently challenged'.

Thank you.

Standardised scores are typically used to allow comparisons across different data sets (or across different time periods). They do this by re-basing sets of raw data on the basis of their averages (means) and standard deviations.

For example, let's assume pupils took 2 test papers, one with a maximum possible 175 marks, the other out of, say, 95 marks. How do we compare overall performance? Well, we could easily compute each individual's percentage. But, if someone scores 75% on each paper, does that mean the relative performance is identical? To answer that, standardisation looks at the distribution of all the data (i.e., takes account of all scores available).

Standard deviations are measures of the distribution of the data. So, if the data is normally distributed, about 68% of the observations would fall within +/- one standard deviation of the mean. (About 95% of all the data would be within +/- 2 standard deviations.) Therefore, for any score, we can work out how far it is from the mean in terms of standard deviations. Armed with this, we now have a better basis for comparison. On paper 1, 75% may place the pupil in the top 10% of all pupils whilst, on the second paper, 75% may place them only in the top 25%. (Indeed, from the actual score, we can determine the exact percentile of any mark.)

From your example above, it looks like the mean is 100 (normal to rebase the mean to 100); the standard deviation is 15 (giving a range from 85 to 115 = 100-15 & 100 + 15). Below 85 places the data more than one standard deviation below the mean (basically bottom 20%), greater than 115 places the data more than one standard deviation above the mean (top 20%).

Hope this helps!

Cor!
What a complicated post.

Yes, it seems complicated until you realise how it works. Worth knowing, though, because standardisation / normalisation is used extensively by exam boards and others.

It also means you often don't get to see raw scores, of course. So, from the outside, you don't really know what's going on.

Ah. Am begining to understand.

Let me see if I have got this right with the example of a school I am familiar with, Graveney (partially selective) in SW London. It is often said that a DC needs to get 98% to get in, which makes it sound as if you have got 2% of the answers wrong - which is near as dammit getting it all right - ie 100% right.

But I think reading around standardised scores that it is impossible to "get" 100%. The most you can "get" is 99% (meaning you are in the top 99 percentile)!

This all makes Graveney admission sound much more achievable than I had (perhaps naively) thought. It seems as if the fabled 98% (the cut-off on offer day) isn't as hard as it sounds (although still hard, not so hard IYSWIM): its not only getting 2% wrong. If I understand correctly: in a test which has say 160 questions - I had thought 98% meant only making four mistakes! But in fact, it seems it means being in the top 2 percentile. And that also adjusted for age.

And that doesn't even mean the top 2 percent of applicants for Graveney on selective criteria. Its the top 2% of all the Wandsworth test entrants - and all Wandsworth year 6 students enter and all others from out of bourough who want a Wandsworth secondary (not just Graveney). So there must be, what?, thousands of children of all abilities doing the test.

On the other hand you still need to be in the top 2% of those taking the test ! :(

as someone who's too lazy to read lots of words, there's a pretty graph here which says it all
www.nfer.ac.uk/nfer/research/assessment/eleven-plus/standardised-scores.cfm