An Open Letter to the Director at N.I.E Sri Lanka
Posted on May 15th, 2016

Jay Deshabandu


Department of Mathematics

Faculty of Science and Technology

National Institute of Education


I became interested in giving a Mathematics contest in order to increase and motivate our students’ interest in learning Mathematics. In order to design a Mathematics test, I read your grade 11 Mathematics syllabus which is officially published by your institute.

In the Statistics part of the syllabus, the definition of a histogram is not what the rest of the world follows. In your syllabus it says that a digram of frequencies verses class widths as a histogram. And, it further clearly indicates that in the case of equal class widths, the area of a bar is equal to the frequency.  In a formal definition of many good books on Statistics, The y-axis is chosen as frequency density-not just frequency. Thus frequency density times the class width gives the area of the bars which is the frequency. Please note that If frequencies are chosen for y-axis, it is called a bar graph not a histogram.

The proper definition is a key to begin a study of probability distributions because in a discrete probability distribution, the y-axis is chosen for the probability density function, which is equal to a histogram where y-axis is chosen as relative frequency density. So the proper definition lends to the idea of probability density function for a discrete random variable.  The idea of a probability density function for a continuous function is an extension of the idea of probability distribution function for a discrete random variable.

Besides, if our students use the definition of a histogram according to your syllabus, they will give wrong answers to international examinations in Statistics such as A-level, Cambridge International Examinations and M.E. I and Edexcel.

I hope that you would pay your kind attention to the above for the sake of Students in Sri Lanka.

One Response to “An Open Letter to the Director at N.I.E Sri Lanka”


    Jay Desabandu, What has your subject in your article relate to what is happening in SL today. I knew you from long time ago. The original Gesabanduva is dead. you took over. What the original Desabanduva did was to edit the constitution and state what a set of idiots wrote this constitution referring to JRJ. You don’t understand head or tail of probability, let alone arithmetic. Long time ago you could fool people with dis-information but not today. Good example in Mangala Samaraweera is asking MR to resign and retire from politics. read Infoflanka article that appeared in Colombo Telegraph!

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