Giving money (like RM500) to people is not helping them; teaching them useful skills is

A real life example.

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An interesting palindromic sequence from a ciliate protozoa

I recently gave a lab session on using dot matrix plots to detect interesting sequence patterns using Dotlet to some students in genetics. A group showed an interesting palindrome from Tetrahymena pigmentosa rDNA, about 250bp long. I did a quick check and found out some interesting things about this organism (such as it is a protozoa, which I didn’t know). It appears to be a well-studied model, attracting attention of people working the J.Craig Venter Institute. Interestingly, one species actually comes from Malacca (T.malaccensis). In 1991, Yasuda and Yao elucidated a mechanism for the production of long palindromes in Tetrahymena that depends on the presence of short inverted repeats. Here’s a diagram showing the result of a dot plot for the Tetrahymena thermophila macronuclear extrachromosomal rRNA gene (GenBank ID: M11155). The sequence is 1935 bases long, and the palindromic sequence is located at position 1200. The complete palindrome is 42 bases long. Note the presence of a repeat upstream.

tetrahymena_thermophila

It is rewarding to be stimulated by students in this way.

Reference: Yasuda, L.F. & Yao, M-C. (1991). Short inverted repeats at a free end signal large palindromic DNA formation in Tetrahymena. Cell, 67:505-516.

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Crime: hit the source not the sink

Regardless of published statistics (which don’t adjust for unreported crimes) that reportedly show that it is getting safer in the streets, events at the ground show otherwise. Neighbourhoods rush to put up their own community barricades, a fresh undergrad is killed by snatch thefts while going to work, a jogger is murdered in broad daylight, a high-ranking government official is shot and killed while on the way to his office – these things are rarely unheard of when I was growing up, but now pepper the front page of newspapers almost on a daily basis.

Contrary to common belief, putting more men-in-blue on the streets will not solve the problem. We can imagine the problem of crime as a pool of water accumulating in a basin. At any time, the amount of water (criminals) in the basin is determined by the rate of water flowing in from the tap (source) and how much get removed via the drain hole (sink). You will agree, that enlarging the drain hole without a concomitant reduction in the rate of flow-in cannot reduce the water level in the basin. The trick is to prevent people from entering into a life of crime at the first place since the odds of reforming a criminal is poor.

The metaphorical tap can be fixed if there are policies of wealth creation that are more equitable, rather than concentrated in the hands of old elites, as it frequently happens in this part of the world. More importantly, don’t forget the teachers, who play crucial roles in preventing a student from entering a life of delinquency. They are actually the front-line fighters against crime, not the men-in-blue, a fact that is sadly overlooked by the policy makers. What goes on today in classrooms can hardly be said to be inspiring. Studying for the sake of examinations has become the norm, and some classrooms are completely devoid of quality instructions. When young minds are left idle for long periods of time, they become breeding ground for all kinds of nasty social experiments, hurtful to themselves and people around them.

The teaching profession no longer receives the cream of society as its apprentices, as it used to be. This is a consequence of the capitalistic economy that rules the world today. As a nation develops, the expanding financial sector (which is very lucrative) sucks up the bright young people, and impoverishes the talent pool in the sphere of public services. This is also true of the quality of research scientists in universities. Of course, there will always be a small group of enthusiastic people who dedicate themselves to the latter, but their numbers cannot hold the ground, and wholesale degeneration of the average quality of these sectors is inevitable. Ironically, it may be in countries that are just about to develop that one may find the best teachers.

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Statistical literacy in society

The hottest news in the campus now appears to surround the latest findings from UM’s Centre for Democracy and Elections (UMCEDEL), which put some quarters ill at ease. You can read about the summary of the findings here. Many news portals quote the UMCEDEL study as reporting that 46% of young voters favour DSAI as compared to 39% for DSNR. Hillariously, this study is immediately attacked for being “flawed”, “insufficiently sampled”, etc, nevermind that the centre has previously published very favourable results for the grieving side.

These responses are reactionary and unwise. Fortunately, one can more or less decide whether to believe the findings by doing some research, with the help of some statistics. The study employed 20 enumerators and they sampled 1407 respondents across major ethnic groups randomly (and presumably, reflecting the ethic composition. However, the slides given in UMCEDEL do not explicitly mention this). The method used was face to face interview, using a structured questionaire. This method seems reasonable, and for now let’s suppose that the experimental design is OK.

Let us assume that the question gave three options (two options for each of the politicans, one for “others”). The standard error (SE) computed under the most conservative assumption (equal support for both politicians), is the square root of 1/4n, where n=1407. The margin of error at 95% confidence, is given by about two times of the SE. A simple calculation shows this to be about 2.6% (let’s take 3%).

However, a look at the UMCEDEL slides suggests that they phrased the question in a more complex way. umcedel_slide
This slide shows tabulated results from the UMCEDEL study, from which we can infer that a respondent was presented with the questions:

1) “Is DSAI your favourite leader?” (Yes,No,Unsure)
2) “Is DSNR your favorite leader?” (Yes,No,Unsure)

whereupon, 46% of them answered “Yes” in Question 1, and 39% of them answered “Yes” in Question 2.

The interpretation of this result is not straightforward. There are actually 9 possible combinations here, and it is not clear how to make sense of some of them (e.g. “Yes”, “Yes”). If I were to set the question, I would just ask them who was their favourite leader, and provide three options, the third being “someone else”. One way to analysis the result is to perform the chi-squared test to test the null hypothesis of equal support, e.g. the ratio of support is 1:1 for DSAI:DSNR.

Anyway, if we collapse the “No” and “Unsure” responses in both questions, then the 95% confidence interval of the proportion of young voters favouring DSAI as their leader is 46%, give or take 53% , which gives a low of 4143% and a high of 5149%. For the DSNR case, we have a low of 3436% and a high of 4442%. Note that the confidence intervals overlap, which may indicate that support for the two candidates is not statistically significant. However it is not clear to me how this can be tested – a two sample Z-test for binomial proportions seems tenuous, as both answers are obtained from the same person and we don’t have independence of samples.
P/S: After correcting for the calculation mistake, it seems that the 95% confidence intervals don’t overlap!

After going through this thinking, does the study really tell us much? It is unclear how the “random” sampling was done (hopefully, it was not haphazard sampling, which is frequently taken to be equal to random sampling!). Were the respondents sampled primarily in towns? hamlets? At what time of the day were the studies conducted? Did the respondents trust the professionalism of the interviewers (i.e. trying to guess what the interviewer’s political inclination and go along with it)? What was the nonresponse rate?

Is there a need to get upset with the findings of the study?

Posted in Coffee talk, Education | 4 Comments

2013 is International Year of Statistics

The International Year of Statistics (Statistics2013)

It’ll be great to join in the fun to hold a series of talks and workshops in R right here.

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Algorithm for teaching

while(TRUE){
Learn new material ;
Teach ;
if(admin work burden > tolerable limit OR distractions == too many) break;
else Update material;
}

Posted in Education | 2 Comments

Einstein’s talk to a group of school children

Most of us remember Albert Einstein as a giant in physics, but from a collection of his writings, he was also very much interested in education and cultural matters. Below is his talk to a group of children in the 1930s – no long-winded moralising sermon (no one remembers long speeches), just a short, powerful reminder that if we ever discover anything new it is because generations of people before us had set up the foundation for it to happen. The one line closing argument is compelling!


My dear children:

I rejoice to see you before me today, happy youth of a sunny and fortunate land.

Bear in mind that the wonderful things you learn in your schools are the work of many generations, produced by enthusiastic effort and infinite labour in every country of the world. All this is put into your hands as your inheritance in order that you may receive it, honor it, add to it, and one day faithfully hand it on to your children. Thus do we mortals achieve immortality in the permanent things which we create in common.

If you always keep that in mind you will find a meaning in life and work and acquire the right attitude toward other nations and ages.

Posted in Education | 5 Comments