A statistical perspective on the 2013 scores

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aang
Posts: 158
Joined: Fri Mar 04, 2011 1:41 pm

A statistical perspective on the 2013 scores

Post by aang »

I have entered the scores posted in this forum into an excel spreadsheet and compared it to previous years'. Here are some of my observations...

1. The results posted in these forums are not a representative picture of the overall results as these forums contain an over-representation of higher scores, 2013 even more so than 2012

Standardised score
2009: mean 347.56, st dev 31.9 (sample size 13)
2010: mean 349.51, st dev 19.0 (sample size 19)
2011: mean 344.18, st dev 21.4 (sample size 49)
2012: mean 340.08, st dev 20.4 (sample size 73)
2013: mean 346.55, st dev 28.8 (sample size 70)

Comparing 2012 and 2013 where the sample size is larger, and hence we can have more confidence into any statistical comparison, the mean standardised score has gone up from a high 340.08 to a really high 346.55. In theory, the distribution of scores from one year to another should be consistent - after all, this is what standardisation is supposed to achieve. Assuming CSSE have not done things differently (!?), then do not overly worry that lots of people in this forum appear to have high scores..

2. The Verbal Reasoning paper in 2013 was much easier than 2012

Mean and standard deviation scores are based on VR raw scores only
2009: mean 70.3%, st dev 13.3%, mean overall standardised score 348 (sample size 13)
2010: mean 78.1%, st dev 9.1%, mean overall standardised score 350 (sample size 19)
2011: mean 79.6%, st dev 10.5%, mean overall standardised score 344 (sample size 49)
2012: mean 74.8%, st dev 10.0%, mean overall standardised score 341 (sample size 73)
2013: mean 77.6%, st dev 15.9%, mean overall standardised score 347 (sample size 70)

A comparison of the mean verbal reasoning shows an increase in the mean of the scores posted in this forum from 74.8% to 77.6%. More telling is if we look at the distribution of the very high scores...

............................................ 2011 2012 2013
Score in VR paper of 95% and above 2% 0% 7%
Score in VR paper of 90% and above 19% 4% 30%
Score in VR paper of 85% and above 31% 16% 38%
Score in VR paper of 80% and above 50% 30% 49%

In 2012 none of the scores posted in this forum scored 95% and only 4% scored 90% or above. The corresponding figures for 2013 showed 7% of candidates achieving 95% and a whopping 30% of 90% (72+/80). There is no reason to believe that the 70 or so candidates last year were of a significantly different ability to this year's.

3 The English paper continues to be the hardest paper with the lowest scores. In these situations, every mark matters so getting the easier spelling and punctuation marks is imperative.
Mean and standard deviation scores are based on English raw scores only
2009: mean 67%, st dev 11%, mean overall standardised score 348 (sample size 13)
2010: mean 66%, st dev 8%, mean overall standardised score 350 (sample size 19)
2011: mean 51%, st dev 11%, mean overall standardised score 344 (sample size 49)
2012: mean 58%, st dev 8%, mean overall standardised score 341 (sample size 73)
2013: mean 53%, st dev 13%, mean overall standardised score 347 (sample size 70)

4. The Maths scores have rebounded following the change in format in 2012
Mean and standard deviation scores are based on maths paper only
2009: mean 65%, st dev 14%, mean overall standardised score 348 (sample size 13)
2010: mean 68%, st dev 17%, mean overall standardised score 350 (sample size 19)
2011: mean 73%, st dev 15%, mean overall standardised score 344 (sample size 49)
2012: mean 64%, st dev 11%, mean overall standardised score 341 (sample size 73)
2013: mean 74%, st dev 13%, mean overall standardised score 347 (sample size 70)

2012 saw the introduction of sequential parts to a question which meant that you really needed to get the first part correct to get the second and similarly to the third part. The mean scores in maths have rebounded from 64% in 2012 to 74% which is similar to previous years.

5. Combining the points above means that a child scoring 26/50 in English, 30/40 in Maths, and 62/80 in VR would result in a standardised score of around 347. Increase or decrease the scores accordingly, but this can help set a target for any child taking the exam next year..
moved
Posts: 3826
Joined: Fri Oct 12, 2007 1:42 pm
Location: Chelmsford and pleased

Re: A statistical perspective on the 2013 scores

Post by moved »

There are many children with scores well below 300, but this forum doesn't have many of them. People tend not to post low scores either.

I know of several with scores well below 290! Some parents put their children in for the test because they took the 11+ themselves, some children want to take the test because their friends are taking it, many are not prepared in anyway at all and some children perform very badly on the day, due to health, family or other issues.

Some children are not aiming for the grammars but would like to be in the top stream at Shoebury or one of the other schools. They may not really be 11+ candidates.

If you want the data it may be worth asking the CSSE if they use a standard normal population curve based around 100. That way we would all know, rather than assume that this is the case.
Chai
Posts: 156
Joined: Sat Dec 06, 2008 2:41 pm

Re: A statistical perspective on the 2013 scores

Post by Chai »

That's very helpful, aang.

Thank you for taking the time to analyse it.
MrsB
Posts: 174
Joined: Wed Dec 21, 2011 11:02 pm

Re: A statistical perspective on the 2013 scores

Post by MrsB »

aang wrote:5. Combining the points above means that a child scoring 26/50 in English, 30/40 in Maths, and 62/80 in VR would result in a standardised score of around 347. Increase or decrease the scores accordingly, but this can help set a target for any child taking the exam next year..
Very helpful analysis, (even if I only understand bits of it :lol: )Also excellent tips on picking up points in English

On your final point about the target, a point for parents to remember when prepping for next year is that most children perform worse on the day, not surprisingly. Every year the board is full of parents saying that there child has never done so badly on VR for example. So to have a realistic chance, the child should ideally be scoring above these figures in practice papers - our DS dipped from 90s to the mid 70s in the actual exam.
Chai
Posts: 156
Joined: Sat Dec 06, 2008 2:41 pm

Re: A statistical perspective on the 2013 scores

Post by Chai »

Hope this helps.

I asked CSSE what the maximum score is for this year.

This is what they said:

The maximum marks achieved varies. This year an extremely small number of candidates did exceptionally well and scored in excess of 400.

I believe maximum is 420 for this year.
CardyMow
Posts: 194
Joined: Fri Jul 13, 2012 11:53 pm

Re: A statistical perspective on the 2013 scores

Post by CardyMow »

There were scores in excess of 400?! :shock:
moved
Posts: 3826
Joined: Fri Oct 12, 2007 1:42 pm
Location: Chelmsford and pleased

Re: A statistical perspective on the 2013 scores

Post by moved »

Statistically there should only be 6 children with scores above 390.

Edit:

Aang would prefer me to let you know that there could be anywhere between 0 and 12 children in this group.
Blitz
Posts: 874
Joined: Wed Aug 25, 2010 3:58 pm

Re: A statistical perspective on the 2013 scores

Post by Blitz »

There are 5 scores of over 390 posted on this forum already. Come on guys who has got the last 'golden ticket' to Grammar school certainty? :lol:
Last edited by Blitz on Thu Oct 18, 2012 8:47 pm, edited 1 time in total.
kaynor
Posts: 157
Joined: Fri Feb 11, 2011 9:50 pm

Re: A statistical perspective on the 2013 scores

Post by kaynor »

CardyMow wrote:There were scores in excess of 400?! :shock:
A little bit frightening isn't it. :)
pg19
Posts: 110
Joined: Fri Oct 12, 2012 8:45 am

Re: A statistical perspective on the 2013 scores

Post by pg19 »

Hi all,
I m a bit confused.
1.how does one calculate the score?
2.how much is the score out of if few children score beyond 400.
thx
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