Wilson mock test results received by email last night

[totatoti]

Standardized score of 70, instead of 100, was used by Wilson's mock based on their written feedback sent together with test result.

My son got overall standardized score of 164 and I can work out it is equivalent to 234 on the basis of standardized score of 100.

You cannot do this without knowing the standard deviation that was used for the standardisation. How do you know what it was in either case?

I dont think I am qualified to discuss about standard deviation but the Sutton mock standardisation was made on average (mean) basis so it is straight forward calculation which I assume Wilson also used. Wilson feedback also stated age factor was not considered in the mock result standardisation. It is a rough straight approach the way I calculated so I can compare Wilson mock with Sutton mocks...

[Guest55]

Standardising includes using the standard deviation - you cannot standardise without it!

[ToadMum]

Standardized score of 70, instead of 100, was used by Wilson's mock based on their written feedback sent together with test result.

My son got overall standardized score of 164 and I can work out it is equivalent to 234 on the basis of standardized score of 100.

You cannot do this without knowing the standard deviation that was used for the standardisation. How do you know what it was in either case?

I dont think I am qualified to discuss about standard deviation but the Sutton mock standardisation was made on average (mean) basis so it is straight forward calculation which I assume Wilson also used. Wilson feedback also stated age factor was not considered in the mock result standardisation. It is a rough straight approach the way I calculated so I can compare Wilson mock with Sutton mocks...

But the 'standardisation' involves calculating and using the standard deviation.

Have a look here at a calculation for our local 11+ in Essex (a real life example, not a mock)
http://www.csse.org.uk/?view=mycomp

Click on 'Preparing for 11+', scroll down to 'Standardisation Report' (ignoring the last bit about multiplying the Maths and English scores by 1.5 - that is a local quirk). True, this calculation doesn't actually give you the formula for calculating the standard deviation,
which is

1. Work out the Mean (the simple average of the numbers)
2. Then for each number: subtract the Mean and square the result.
3. Then work out the mean of those squared differences.
4. Take the square root of that and we are done!

(https://www.mathsisfun.com/data/standar ... mulas.html)

Obviously, that bit is for whoever does the statistics for the respective organisations to sort out, though .

[Guest55]

Once you have the mean and standard deviation you then have to use these to standardise the raw marks.

The point of this is to turn a Normal distribution of marks into a Standard Normal distribution so that the correct proportion 'pass' or 'qualify' depending on which test we are talking about.