Tuesday, January 17, 2012

Z Score Imbroglio

, The Island.

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by Prof. R.O. Thattil

I am writing this article to clarify certain matters raised at different forums, some in the form of allegations.

The Secretary of the UGC stated on TV (Rupavahini programme held on 14 January, 2012) that I had not been invited to the committee because I submitted a document that the Z score was incorrect in a court case a few years back.  This is totally untrue.  How could I go against the Z score that I advocated a decade ago?  What really happened was I submitted a document stating that individual Z scores received for each subject should not be rounded off to the second decimal place before calculating the final average Z score.  The computer can hold many decimal places! The rounding off error can go up to 0.005 which can decide the future of one or more students. Who rounds off intermediate calculations anyway when using a computer?

 The second statement he made was that I was against the UGC since I had not been reappointed for a second term as Director of the Postgraduate Institute of Agriculture. What has this got to do with my speaking for justice?  If something is wrong one has a right to point it out.  The statements made by the Secretary and a few others try to distract the attention of the public from the main point; namely the error in pooling means and standard deviations from the old and new syllabuses of a subject in formulating the Z score.

The committee appointed by the President to look into the problems in releasing the A/L results, has stated that everything has now been corrected.  However, they avoided the key question about the error in pooling.  Perhaps, they were not mandated to do this.

A member of the committee that suggested pooling, stated that there is not much of a difference whether it was pooled or not.  If so why choose the wrong method (pooling)?

Saying that there is not much of a difference is a feeble excuse.  The so called small difference could affect a large number of students.  I have shown in an article written in this Newspaper (13/01/2012) how pooling affects the Z scores.  Some persons have reacted to this by saying it is only an example.  True it is an example, but in theory too, when 2 means are pooled, the pooled mean will always lie between the 2 means! This is what leads to the discrepancies.

A Minister of the Government has stated that I was not the founder of the Z score but it was someone else in Sri Lanka!  No one can claim to be the founder of the Z score which has been used for over a century.  It may be Sir Ronald Fisher (the father of Modern Statistics) who used it first for scaling variables.  However, I am the person who proposed the Z score to scale marks in 2000 for the A/L examinations, so that the average of the Z scores received for different subjects can be used in ranking.

 I fervently hope that the main issue of pooling will not be clouded by arguing on irrelevant issues. Let justice be done!

A/L results fiasco, President to take appropriate action

Though the five member committee that probed the 2011 GCE Advanced Level results fiasco held certain officials at the data processing unit of the Examination Department responsible for the blunder, it was up to the President to take appropriate action against them, committee secretary Dhara Wijetilaka said today.

“Since the committee was appointed by President Rajapaksa, the report was handed over to him and it is up to him to act accordingly,” Mrs. Wijetilaka said.

“We are not ready to comment on the findings or recommendations of the report or to make it a public document. It is entirely the responsibility of the Presidential Secretariat to act on the recommendations and release it to the public,” Mrs. Wijetilaka stressed.

Asked as to why the committee did not inquire into the core issue, the controversial Z-score, she said the committee was not mandated to pass judgments on the Z-score and therefore did not invite Prof. R.O. Thatil who reportedly invented the Z-score for University enrolment in Sri Lanka. (Sandun A. Jayasekera)

Z-score - Ranil to make statement in Parliament

Print
UNP leader Ranil Wickremesinghe will make a statement in Parliament today on the crisis of the Advanced Level results, the party said yesterday.

Chief Opposition Whip John Amaratunga said that his party would also move a motion for the appointment of a select committee to study the reasons that led to the crisis. Mr. Amaratunga said that the party would hand over the motion to Speaker Chamal Rajapaksa in terms of normal procedure.

The select committee is expected to study the modalities of the calculation of the Z-score marks of students sitting the Advanced Level examination, and to make recommendations to avoid repetition of such problems hereafter. (KB)

FUTA token strike today despite pay hike circular increasing

, The Island.

by Dasun Edirisinghe

University teachers will stage their previously scheduled token strike in universities countrywide today even though the University Grants Commission issued a circular increasing salaries on Friday.

President of the Federation of University Teachers Associations (FUTA) Dr. Nirmal Ranjith Devasiri told The Island that their main objective for staging a token strike was to get

the private universities bill abolished.

He said however, they would not accept the salary increment given in that circular.

According to the circular, Dr. Devasiri said, senior professors get a 16 per cent salary increment, but junior lectures get only 3 per cent.

"There are only 30 senior professors in the country," he said.

However, the increment mentioned in the circular would be granted only from August in two steps, the senior academic said.

Dr. Devasiri said that they were only considering a salary revision which was in the agreement entered between the FUTA and the Higher Education Minister when they suspended the trade union action in July, 2011.

He said according to that agreement the salary problem would be solved by four steps and now is the time to implement second step which add 20% increment to the basic salary of all university lecturers.

"We will go ahead with scheduled token strike today," Dr. Devasiri said adding higher education minister’s assurance to abolish the propose bill is the only way to stop it.

He said that they also demanded increment some academic allowances and allocate 6% to the higher education sector from the Gross Domestic Production (GDP).

Z score and populations

, The Island

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by Nalin de Silva

I would not have written this if not for the explanations given by Prof. Thatil on the Z score. He has referred to the formula used by the panel of experts on pooling of two populations and said that it is not correct to pool them and then find the Z score of the pooled populations. Instead he suggests that the Z scores of different subjects of the two populations should be taken as they are and then add the Z scores of the three subjects each student has sat and then find the average of the three Z scores. The panel on the other hand pools the populations that sat the old syllabi and new syllabi examinations, find a Z score in each subject for the pooled populations and then take the average of the three Z scores to determine what is called final Z score of a student.

However it is the addition of Z scores in separate subjects that is questionable rather than the pooling of two populations. What is forgotten in the whole exercise is that what we are interested in selecting the students who performed better at the GCE (A/L) examination. Even if we have a group of students who sat for the same three subjects in the new syllabi how are we going to select the better students? Consider the following two cases. Sandun obtains 90 marks for Combined Mathematics 80 for Physics and 40 for Chemistry, while Sanduni obtains 60 marks for Combined Mathematics 70 for Physics and 85 for Chemistry. If we go by the aggregates of marks Sanduni is the better student. If the Z scores are considered this order may be reversed. However we cannot select the better student even by adding the respective Z scores. How does one compare the Z score in Chemistry with that in Physics? In other words how many marks in Chemistry are equivalent to say 70 marks in Physics?

If Sandun has 90 US Dollars, 80 Pounds and 4000 SLRupees  and Sanduni has 60 US Dollars, 70 Pounds and 8500  SLRupees we can find out who has more money by converting each currency to a common currency using the current exchange rates and then adding the money in the common currency. My question is what the exchange rates are as far as marks obtained in different subjects are concerned. I do not think that the Z scores give an "exchange rate" in respect of marks obtained in different subjects.

This problem arises not only at selection of students to the Universities but even at term tests in schools. We may say Sanduni came first and Sandun came second by just adding the raw marks. However it may not be so and I suppose in order to overcome this problem some schools adopted a method called scaling of marks in the fifties. The idea was again, I am assuming as I had not discussed this problem with any of the teachers, to find exchange rates between marks in different subjects. It may not be a bad idea for the experts in Statistics to find these exchange rates at least from a literature survey, if they are available, to be used at future examinations.

Though Prof. Thatil may not have realized it, when we calculate the average mark in a subject that is examined using more than one question paper we pool two or more populations and obtain the combined average. For example, though the same students sit for Combined Mathematics I ("Pure Mathematics") and Combined Mathematics II ("Applied Mathematics") they cannot be considered as one population. They are two populations but we consider them as one population for the purpose of calculation of the average mark in Combined Mathematics and then calculating the mean and variance in order to find the Z scores in Combined Mathematics. It would have been better if we have an exchange rate for conversion of marks from Combined Mathematics I to Combined Mathematics II and vice versa but until such exchange rates are found we may have to pool populations whenever pooling is better than any other method available.

UGC chief defends tough action at universities

‘Deal with simmering crisis now or face the consequences’

, The Island.

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Deans of Sri Jayawardenapura University together with the Vice Cancellor meet President Mahinda Rajpaksa on Monday at Temple Trees. Higher Educational Minister, S.B. Disanayaka, Secretary to the President, Lalith Weeratunga and the Secretary to the Ministry of Higher Education, Sunil Jayantha Navarathna were present. Seated neat to Minister Dissanayake is Prof. Gamini Samaranayake.

(pic Chandana Perera)
by Shamindra Ferdinando
Chairman of the University Grants Commission Prof. Gamini Samaranayake yesterday (16) strongly defended tough action taken by University administration to thwart the JVP and so-called JVP rebels from causing mayhem at higher education institutions.

The veteran educationalist emphasized the pivotal importance of tackling troublemakers, regardless of political consequences in a brief interview with ‘The Island’. The failure to curb their despicable strategy would be catastrophic, Prof. Samaranayake said, while acknowledging the right of the student community to engage in politics. But that shouldn’t be the exclusive prerogative of the JVP and other like-minded elements.

The UGC chief was responding to National Freedom Front (NFF) leader and Housing Minister Wimal Weerawansa’s allegation that universities were in turmoil today primarily due to shortcomings on the part of administrators. The former JVP firebrand also accused a section of the administrators of being unfair and irrational in their decision making, thereby causing the rapid deterioration of the system.

Higher Education Minister S. B. Dissanayake, too, is a proponent of tough action against those causing disturbances at universities. During a visit to the Faculty of Applied Sciences, Vavuniya, Minister Dissanayake vowed not to succumb to those seeking to undermine university administration.

In a letter dated Jan. 13, addressed to President Mahinda Rajapaksa, parliamentarian Weerawansa urged tough action against university administrators responsible for the chaotic situation at universities. The MP accused administrators of driving students into the hands of disruptive political elements.

Prof. Samaranayake insisted that it would be a grave mistake on the part of the government to allow those bent on subverting democracy to run universities. The country couldn’t afford to turn a blind eye to bankrupt politicians exploiting universities and schools to pursue their sordid political projects, which would only result in chaos in post-war Sri Lanka, Prof. Samaranayake said.

Referring to a meeting he had with former Chairman of UGC, India, Prof. Samaranayake said that the Indian official thrice stressed the need to take stern action to ensure discipline at higher educational institutions. Asked whether a special strategy was needed to tackle trouble at universities, Prof. Samaranayake advocated a two-pronged strategy to deal with the situation. The university administrators had no option but to take stern action, regardless of political consequences, when handling issues created by the Inter University Students’ Federation (IUSF) at the behest of external elements. "But in case of an issue involving the administration and the student community we could be flexible," Prof. Samaranayake said, while pushing for a no-nonsense approach towards the situation created by the JVP.

The JVP would push hard, real hard to take control of the situation. Although it wouldn’t be able to achieve the capacity to launch an armed insurrection, they could cause a severe crisis by a sustained mass protest campaign targeting the incumbent government. They wouldn’t mind taking casualties as long as they believed their destabilization strategy could succeed, the official said. Although the circumstances were different, the JVP could again exploit both universities and schools as it did in 1971 and 1987-1990, he said. Marxism could be irrelevant in many parts of world, though the JVP remained a significant factor in universities due to their clever strategies.

The JVP considered universities as safe havens for their sordid operations and used them as a springboard to advance political strategies, the UGC head said. Asked whether the threat posed by the JVP was different from that of the LTTE, Prof. Samaranayake said that both could be equally disruptive, though their strategies were different. The JVP never had an opportunity to achieve the LTTE’s conventional military capabilities, though the destruction caused by the group during its second abortive insurgency was extensive, he said.

Prof. Samaranayake said that nothing could be as bad as ignoring ongoing JVP efforts to ignite universities. Unless corrective measures were taken immediately, though they may not be to the liking of some, the situation could develop into a mega crisis. The need was to deal with the threat firmly, thereby thwarting possible future catastrophy, which could require drastic measures to contain, Prof. Samaranayake warned. The UGC pushed for cohesive action to clear universities of troublemakers. The universities couldn’t be run at the behest of the JVP and likeminded groups, he said.