Tuesday, May 13, 2014

Loksabha Elections 2014: My Chinese arithmetic

Yesterday all the phases of polls closed in the country and all the television channels were out with their voodoo science that they call exit polls. Since everybody seem to be doing it, I thought I should also do it. So here it goes.

Exit polls have been wrong in pretty much all the elections in past. Here is a snipped of how exit polls have performed in past.

As we can see in the chart above, there has always been a significant difference in the exit poll results and actual results. Barring 1998, BJP has been always over-estimated in exit polls while congress has always been underestimated in exit polls. So, let's look at kind of error that has been seen in exit polls and actual results.

In the chart above, select Errors for Size, Actual for Y Axis and Time for X axis and click on Play and then we see that both BJP and congress seem to have increasingly higher errors over the years with BJP being over-estimated and congress underestimated.


So, I have decided that I am going to take the average underestimation for congress and BJP from 2004 and 2009 and try to predict the result for this year.

  • Average BJP overestimation = 27%
  • Average Congress underestimation = 21%
  • Average seats predicted for BJP in this year's exit polls = 273
  • Average seats perdicted for congress in this year's exit polls = 110
So my predictions for BJP and congress are as follows.

Thursday, April 3, 2014

India Elections Tidbits #2: Margin of victory

Psephology in Indian elections of always interesting. Television commentators and professors from some mathematics istitute discus on television as if what they discovered is a forgone conclusion. I have heard statements like "Now that congress has lost it, what next for them?".
Winning margin for constituencies with less than 5% margin
Following is the list of constituencies with the winning margin.

Constituency NoConstituencyStatePercentage Margin
5ZahirabadAndhra Pradesh1.71%
6MedakAndhra Pradesh0.57%
10ChelvellaAndhra Pradesh1.60%
11MahbubnagarAndhra Pradesh2.43%
12NagarkurnoolAndhra Pradesh4.66%
23KakinadaAndhra Pradesh3.53%
24AmalapuramAndhra Pradesh3.91%
25RajahmundryAndhra Pradesh0.21%
27EluruAndhra Pradesh3.97%
28MachilipatnamAndhra Pradesh1.19%
29VijayawadaAndhra Pradesh1.17%
30GunturAndhra Pradesh3.77%
31NarasaraopetAndhra Pradesh0.15%
37HindupurAndhra Pradesh2.22%
40TirupatiAndhra Pradesh1.82%
42ChittoorAndhra Pradesh1.02%
43Arunachal WestArunachal Pradesh0.46%
45KarimganjAssam1.16%
50BarpetaAssam3.38%
51GauhatiAssam1.07%
53TezpurAssam3.58%
54NowgongAssam4.54%
57DibrugarhAssam4.68%
58LakhimpurAssam4.90%
69KatiharBihar1.88%
74VaishaliBihar2.70%
79HajipurBihar4.45%
89PataliputraBihar3.75%
100South GoaGoa4.60%
102BanaskanthaGujarat0.84%
105SabarkanthaGujarat2.39%
118PanchmahalGujarat0.19%
126ValsadGujarat0.51%
129SirsaHaryana2.41%
147ChikkodiKarnataka4.42%
149BagalkotKarnataka2.47%
157DharwadKarnataka3.70%
163Dakshina KannadaKarnataka3.22%
167MysoreKarnataka1.70%
170Bangalore NorthKarnataka3.62%
172Bangalore SouthKarnataka2.90%
180MalappuramKerala0.00%
183AlathurKerala2.53%
184ThrissurKerala3.20%
186ErnakulamKerala1.58%
196BhindMadhya Pradesh4.38%
203SatnaMadhya Pradesh0.44%
209BalaghatMadhya Pradesh3.82%
216UjjainMadhya Pradesh4.48%
218RatlamMadhya Pradesh4.65%
222KhandwaMadhya Pradesh4.28%
224NandurbarMaharashtra3.97%
228BuldhanaMaharashtra3.29%
253Mumbai South CentralMaharashtra4.93%
264LaturMaharashtra1.51%
276MizoramMizoram0.00%
286DhenkanalOrissa2.17%
287BolangirOrissa4.82%
289NabarangpurOrissa0.00%
295BhubaneswarOrissa1.46%
303HoshiarpurPunjab2.93%
308FerozpurPunjab2.20%
339Chennai NorthTamil Nadu2.90%
340Chennai SouthTamil Nadu4.52%
342SriperumbudurTamil Nadu2.23%
344ArakkonamTamil Nadu1.41%
350ViluppuramTamil Nadu0.35%
360KarurTamil Nadu3.12%
362PerambalurTamil Nadu0.95%
368SivagangaTamil Nadu0.43%
370TheniTamil Nadu0.41%
380KairanaUttar Pradesh3.10%
381MuzaffarnagarUttar Pradesh1.60%
401BadaunUttar Pradesh1.96%
408SitapurUttar Pradesh2.79%
423JalaunUttar Pradesh0.91%
433Ambedkar NagarUttar Pradesh1.87%
437GondaUttar Pradesh1.37%
449SalempurUttar Pradesh4.64%
480JadavpurWest Bengal4.54%
483HowrahWest Bengal3.75%
484UluberiaWest Bengal4.64%
509MahasamundChattisgarh4.11%
523LohardagaJharkhand1.45%
In summary, based on last election, there are 149 constituencies which were won with less than 5% margin.

  • Less than 1% margin  -- 16 seats
  • Between 1% and 2% margin -- 19 seats
  • Between 2 % and 3% margin -- 30 seats
  • Between 3% and 4% margin -- 36 seats
  • Between 4% and 5% margin -- 48 seats
With such a large number of seats won with so low margin, how can these television commentators be so confident of seats won. Also how can they take the margin of error in votes polled and extrapolate that to number of seats.