Standardised scores are not the same as examination marks

Jul 12, 2026 Features / Columnists, Peeping Tom

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(Kaieteur News) – Every year, when the National Grade Six Assessment (NGSA) results are announced, many parents and students naturally ask the same questions. How were the scores calculated? Did the students who tied for first all receive the same examination marks?

And how can several students obtain the highest possible score? The answers lie in understanding standardised scores.

At first glance, the term sounds technical and intimidating, but the idea is actually quite straight forward.

When a student sits an examination, he or she earns raw marks. These are simply the actual number of questions answered correctly or the total marks awarded by the examiners. If a Mathematics paper is worth 100 marks and a student earns 92, then the student’s raw score is 92.

A standardised score is something entirely different.

Rather than reporting only the raw marks, statisticians convert those marks into a scale that allows students to be compared fairly across subjects and across the entire group of candidates. This process takes into account not only how well a student performed but also how everyone else performed.

To understand why this is done, imagine two examinations.

Suppose one year’s Mathematics paper turns out to be unusually difficult. The highest raw mark earned by any student is 83 out of 100. The following year, the paper is easier and several students score 98 or 99.

If only raw marks were used, students in the second year would appear to have performed much better, even though the examinations were not of the same difficulty. Standardisation helps overcome this problem by placing performances on a common scale.

In simple terms, standardised scores measure relative performance, not simply the number of marks obtained. This is why a standardised score should never be mistaken for an examination mark.

A student may receive the maximum standardised score without achieving full marks on every paper. Likewise, another student may have higher raw marks in one subject but a slightly lower standardised score after the statistical calculations are completed.

This also explains another question that often arises whenever results are released.

If, for example, about 15,000 students sit the examination and 20 of them receive the highest possible standardised score, does this mean all 20 earned exactly the same raw marks?

The answer is no.

A standardised score is not a photocopy of the raw marks. Different combinations of raw marks can produce the same standardised score once the statistical conversion has been applied.

One student may have scored slightly higher in Mathematics and another slightly higher in English, yet after standardisation both may arrive at exactly the same overall standardised score.

Think of it like converting temperatures from Celsius to Fahrenheit. Different calculations can produce values that are equivalent on a different scale. Similarly, standardisation transforms raw marks into another measurement designed for comparison rather than simply recording the original marks.

Some people also wonder whether having 20 students tie for the highest standardised score is unusual.

Not necessarily.

In a cohort of approximately 15,000 students, 20 students represent only about 0.13 per cent of all candidates—roughly one student in every 750.

Statistically, this is still an extremely small group.

Whether 20 students achieve the maximum standardised score depends on several factors, including the overall ability of the cohort, the distribution of marks, and the statistical method used in standardisation. If many of the strongest students perform at an exceptionally high level and their performances are virtually indistinguishable after the statistical adjustments, it is entirely possible for several of them to share the highest standardised score.

In fact, educational testing programmes around the world regularly produce ties at the top. This occurs because standardisation often compresses tiny differences in raw marks that are not considered educationally meaningful.

For example, if one student scores 98 and another scores 99 on a paper, the statistical difference between those performances may be so small that, after standardisation and combining results across subjects, both students receive the same final standardised score.

This does not diminish either student’s achievement. Instead, it reflects the reality that both performed at an exceptionally high level.

A common misconception is that if two students receive the same overall standardised score, they must have obtained the same total raw marks across the four examination subjects. This is not necessarily true. Standardisation is carried out separately for each subject, converting raw marks into standardised scores that reflect a student’s performance relative to the rest of the cohort in that subject.

Those standardised scores are then combined to produce the overall result. Consequently, two students may have different raw marks—and even different total raw marks across all three subjects—but still end up with the same overall standardised score because their performances, once adjusted for the distribution of marks in each subject, are considered statistically equivalent. In other words, a standardised score reflects relative performance rather than the simple sum of the actual examination marks.

It is therefore important to avoid assuming that students with identical standardised scores necessarily earned identical raw marks. Equally, students separated by only one standardised point may have raw marks that differ by more than people imagine—or by much less. The standardised score alone does not reveal the underlying examination marks.

Parents and students should therefore view standardised scores as a statistical tool rather than as a report of the actual marks obtained.

The examination scripts are marked using raw scores. The published results, however, are based on standardised scores. Although related, they are not the same thing. Understanding this distinction helps to explain why several students may share the highest standardised score without necessarily having written identical examinations or achieved identical raw marks.

The views expressed in this article are those of the author and do not necessarily reflect the opinions of this newspaper

 

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• Peeping Tom

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