Every test score has the potential to be affected by chance errors.
“You obtained 76% last week. What has happened, you only achieved 74% today?”
“But that digger is still digging up the road outside, the cat demands to sit on my lap – and anyway I don’t feel all that well. I told you that before I went to school this morning.”
A testee can be affected by noise, or feeling slightly off balance. There may have been a fight at school with a `best friend’. Even misreading a question can affect a test result.
There can even be errors arising directly from the test. A question may be ambiguous or phrased in an exceptional manner. The 76% reached last week may have been an over estimation – and not a true reflection. (The mother may not have remembered that last week she gave some help on a group of questions – but did not offer the same help this week.)
Some children may even be a little careless in answering some types of question. There may be some questions which are so `easy’ that the candidate may not have noticed the `not’ hidden in the middle of the sentence.
Some types of question may not `suit’ the child. In non-verbal reasoning, for example, we meet the infamous cubes. Some children may see these immediately while others cannot see the solution even when standing on their heads.
Statisticians are able to distinguish between a true score and an expected score. This would be the score that your child obtained and the hypothetical score that could be obtained if there were no outside influences. The statistician looks at the variance between the scores and then looks to try to see reliability of the obtained data.
There may be some parents who would prefer not to make a statistical analysis – but take the `easy’ way out by saying: “Well dear, that did not go quite as well as last week. I am sure you did your best. There is nothing I could do about the digger and I can make sure that the cat is shut away in a different room. I am sorry that you were not feeling well today. Do we need to cancel your swim tonight?”
“Oh no – I am feeling fine now. I really want to swim. Please don’t stop me. I will do better next week.”