Is the KCSE ranking of schools fair?
The Sunday Nation
Nairobi,
13 March 2011
Last week’s story about paper sizes left one point out: the international “A” series has the additional advantage of getting the mass of a sheet quickly. The most common office paper is the “photo-copy” type which weighs 80 grams per square metre.
This is usually written as “80gsm” and if you have been reading this column long enough you will know that 80gsm is complete nonsense: it means 80gram-second-metres!
Nevertheless, in last week’s article, we found that A0 has an area of one square metre. Therefore, the mass of an 80gsm A0 sheet must be 80g. Since A1 is half the size of A0, it mass must also be half that of A0; that is, 40g.
By similar argument, the mass of A2 is half that of A1 (or a quarter that of A0); that is 20g. Following this progression, it turns out that the mass of the common A4 sheet must be a sixteenth of A0, or 5g. Thus a ream of 500 A4 sheets should weigh 250g – a quarter kilogram.
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Writing from Nyeri, Clement Wanjohi is concerned about the recently released Kenya Certificate of Secondary Education (KCSE) examinations results. He notes that the top student had a mean score of 87.10357 and “from my calculations the top score should be 84 because since grade A is 12 points. There are 7 subjects [and] 12 x 7 = 84 points. Where are the extra 3 points coming from?”
The Kenyan National Examinations Council does not explain how the
“Performance Index” is calculated. I have checked their website and
there is no information. Upon further search on the Internet, I came
across an academic paper
presented at the 27th Annual Conference of the
Association for Educational Assessment in Africa (A.E.A.A) in
The paper was presented by Mwai Nyaga and Hassan Bundu and in it they
write: “The
candidates’ performance index is determined by first converting each
candidate’s marks to percentage scores because all subjects are not
marked out of the same mark. After this is done, the total percentage
marks for the best seven (7) subjects … are added and the total divided
by 7…”
Clearly, since the performance index is a percentage, it can be grater
than the maximum 84 points obtained from the grades.
On the performance index of a school, Nyaga and Bundu write: “To
determine the performance index of each school, the overall mean grades
for each candidate are added and divided by the total number of
candidates in the school…” This is why school performance indices are
always less than 12.
Now a question arises: is it fair to rank candidates on a (weighted)
percentage index and schools on a grade index?
If what Nyaga and Bundu say is
true, that is “all subjects are not marked out of the same mark”, it
means that some of them carry more weight than others.
In that case I don’t think it is fair to use the grade index for schools. If the (weighted) percentage index was used, I wouldn’t be surprised to see changes in the rankings.
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