Bilang Pilipino SWS Mobile Survey an evil perversion of the science of Statistics!

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I am a statistician. I am a graduate of the University of the Philippines School of Statistics. I do not approve of the methodology of the Bilang Pilipino SWS Mobile Survey. More importantly, I detest their use of Statistical methodologies to lend credence to their obviously flawed methodology. It obfuscates its lack of credibility by invoking Statistical methodologies that are not easily understood by many Filipinos. In my opinion, it is a blatant and deplorable misuse of the Science of Statistics.

The Bilang Pilipino SWS Mobile Survey claims that it has a margin of error of +/- 3%. The implication here is that the results of the survey are off by at most three percentage points. People are led to believe that the survey has accurately estimated the lower bound and upper bound of the vote share of each candidate. Given their latest results this would suggest that Sen. Poe has a range of 31% to 37% and Mayor Duterte has a range of 28% to 34%. Here is an explanation as to why I find it absurd.

Students of Statistics know that the margin of error in sampling is often computed as the reciprocal of the square root of the sample size. The Bilang Pilipino SWS Mobile Survey had a grand total of 1,200 possible respondents. SWS has not divulged the number of actual respondents of their latest survey so let us use the sample size in the March 22 survey – 806. If you take the reciprocal of the square root of 806 you’ll get 3.52% (Right off the bat SWS rounded their margin of error down – but let us not quibble over relatively trivial details such as this). Notice that the margin of error does not use the size of the population as a variable (It does not matter if the voting population is 1 million of 50 million). It may come as a surprise to many of you that this isn’t the crux of the issue.

The crux of the issue is that the validity of the aforementioned margin of error depends on the sampling methodology. The margin of error will only hold if the survey is conducted using an unbiased methodology. Put simply, the margin of error will only hold if the survey results are generated from an unbiased sample. What exactly is an unbiased sample? An unbiased sample is one wherein every element of the population has an equal chance of being selected. I repeat: An unbiased sample is one wherein every element of the population has an equal chance of being selected.

Here’s the rub: in order for the margin of error to be credible, the underlying sample has to represent the entire Philippines. How could it represent the entire Philippines when millions upon millions of validated voters were not given a chance to be selected?

Herein lies the test as to whether or not the SWS Bilang Pilipino Mobile Survey should be believed. Herein is a simple question that would tell us whether or not we should lend credence to the results being promoted by this survey: Was every validated Filipino voter given an equal chance of being selected?

According to the SWS Bilang Pilipino primer the survey uses a ‘nationally representative sample of 1,200 validated voters’. The question here becomes: Did SWS draw its 1,200-strong sample from the entire roster of validated voters? After all, each and every validated voter has to be given an equal chance of selection. There is no indication, at all,that SWS sampled from the entire voter registry (As a segue ask yourselves: would COMELEC have given SWS, a private entity, free reign over the ENTIRE voter registry? Hmm.).

This suggests that SWS did NOT give all validated voters a chance to be selected. If this is indeed the case then the SWS Bilang Pilipino survey should not be trumpeted as a credible survey with a very small margin of error – because the sample was BIASED.

It gets better (worse), SWS generates its samples according to strata – or groupings. For the SWS Bilang Pilipino Mobile Survey it used four strata – NCR, Balance of Luzon, Visayas, and Mindanao. There is nothing wrong with using strata and employing stratified random sampling. There is, however, something very wrong about giving these strata equal weights. For its Bilang Pilipino sample, SWS gave NCR, Balance of Luzon, Visayas, and Mindanao 300 samples each. This distribution means that NCR, Balance of Luzon, Visayas, and Mindanao are all given equal weights. The problem here is that the distribution of the Filipino population – and consequently the Filipino voting population is not spread equally across the four strata! Here are approximate values: Balance of Luzon has 44%-45%, Visayas has 20%, Mindanao has 23%-24%, and NCR has the remainder. Putting all of these together we see that Balance of Luzon is severely under-weighted and under-represented and NCR is severely over-weighted and over-represented. BIAS.

The choice of the level of stratification is also dubious given that geography plays a key role in determining the outcome of national elections. National politicians often have home provinces and regions that would lend them tremendous amounts of support during elections. Choosing our island groups as the stratification level ignores the highly nuanced dynamics of local Philippine politics. You do not need to be a political scientist of statistician to realize that this is a poor way of distributing your sample. It is, for example, distinctly possible to generate a Balance of Luzon sample without Ilocos Norte. It is distinctly possible to generate a Balance of Luzon sample without Camarines Norte/Sur. It is distinctly possible to generate a Visayas sample without Capiz. It is distinctly possible to generate a Mindanao sample without Davao del Sur. The choice of stratification assumes that voting preferences within each island group are largely homogeneous. It assumes that there is little to no heterogeneity within each island group.

But wait, there’s more!

The SWS Bilang Pilipino Mobile survey is an opt-in survey. As I indicated earlier, the actual sample could be smaller than the indicated sample. The people who were given mobile phones to respond to text prompts could choose NOT to answer the text prompts. Given the nature of the survey they cannot re-sample to fill-up the desired or indicated sample size! This is obviously another source of bias!

It is also of note that respondents can only respond from 7:00 am to 12:00 noon. If you fail to respond during that window you are excluded from the actual sample. If you forgot to charge the phone, if you could not get a signal, if you were busy at work, if you were sick, it doesn’t matter – you are excluded. Bias, bias, bias!

The survey serves no discernible function. It provides no discernible benefit. One can even make a compelling argument that the SWS Bilang Pilipino Mobile survey is designed to condition the minds of voters and establish trends that would legitimize or sanitize fraudulent election outcomes. I urge you: Do not lend this survey any ounce of credibility.

Voters should not choose their candidates on the basis of who is ‘winnable’ and who is ‘not winnable’. Your choices should not be about who can or cannot win. Elections should be about visions, platforms, and track records. Do NOT reduce the elections into a popularity contest wherein the winners are not chosen based on their capacity to govern – but rather by their perceived popularity. Do NOT cheapen our democracy.

Do yourself and the Philippine democracy a favor: Do not let this survey affect your choices. Think for yourself.

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8 Comments on “Bilang Pilipino SWS Mobile Survey an evil perversion of the science of Statistics!”

  1. No one in their right mind believes SWS anyway. They want to sway daft Filipinos to vote for the one who is leading in their poll. “Oh, that candidate is on top, I will vote for him/her”.

    It wont work, people made up their mind on who to vote for and it’s Duterte and Marcos.

    The best way to determine who will win is talking to taxi drivers. Taxi drivers ask all their passengers who are from all walks of life who they will vote for.
    8 out of 10 say Duterte.

    Even 7/11 is more precise. They are all over the country. Guess who is leading?
    End of story.

  2. Now, this is the most useful, most important write-up that has come out for election2016. It has 0.000001% margin of error. Thanks, David.

  3. Now, please make sure the following are in your list for SENATORS:

    1. Alunan, Rafael III
    2. Gordon, Richard
    3. Osmeña, Sergio III
    4. Liban, Dante
    5. Romulo, Roman
    6. Ople, Maria Susana
    7. Romualdez, Ferdinand Martin

    Among all the candidates, they are the most qualified with proven experience.

    Let us stop putting bozos in that body.

  4. Voters should not choose their candidates on the basis of who is ‘winnable’ and who is ‘not winnable’. Your choices should not be about who can or cannot win. Elections should be about visions, platforms, and track records. Do NOT reduce the elections into a popularity contest wherein the winners are not chosen based on their capacity to govern – but rather by their perceived popularity. Do NOT cheapen our democracy.

    That is highly improbable, given how similar the candidates’ so-called platforms are. They are virtually interchangeable. Consider what was said during the debates.

    Practically all of them want to continue and even expand the government’s flagship anti-poverty program, Pantawid Pamilyang Pilipino Program (4Ps).

    All of them profess to support the passage of the Freedom of Information law.

    The majority hint at amending the racist economic provisions of the 1987 Constitution and implementing tax reforms.

    They all consider agrarian reform — which has been a dismal failure for the past three decades — an essential part of development. Grace Poe, in particular, promises to throw an additional 1.8 Trillion (with a ‘T’) Pesos at the program over six years.

    All the candidates hint at their preference for ASEAN economic integration.

    And yet no candidate can provide a comprehensive plan to implement these promised socio-economic reforms aside from the vague notion that electing them to the presidency will enable them to ‘take care’ of the rest of us. Not one is able to offer the kind of policy changes or political reforms that would enable these dramatic anti-poverty policies they are proposing.

    Like the Mobile Survey, it can be entertaining but hardly illuminating and quite possibly, highly deceptive.

    1. Just a point of clarification.

      Grace Poe’s campaign promises to allocate up to 1.8 Trillion Pesos of government funds for the agricultural sector over six years. Not the agrarian reform program alone.

  5. “Statistics…Statistics…and damn Statistics”….from the American Humorists : Mark Twain.

    Surveys can be used as a campaign tool , by any candidate. Just produce favorable ratings, to encourage everyone to vote for the winning candidate. The other candidates, do not have a chance: so we are just “wasting” our votes.

    Sampling can be done in any manner, as done by the one doing the sampling. Random or biased, it does not matter. Almost everybody, does not know how they did it.

    Anyway, they did not take into consideration these factors:

    1. The HOCUS PCOS Machine.

    2. The Dead can vote.

    3. Flying voters.

    4. Terrorising voters.

    5. “Dag dag, Bawas” tactic…

    Happy election…

  6. There are three types of lies — lies, damn lies, and SWS/Pulse Asia statistics.

    Facts are stubborn things, but SWS/Pulse Asia statistics are pliable. All SWS/Pulse Asia statistics have outliers.

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