Do voters vote for parties or individuals? Do national issues like immigration or local issues like traffic matter more? On one hand, "macro" issues like the branding and track record of a political party, as well as the direction national policies are taking, must carry some weight with voters. On the other hand, voters are surely concerned about their day-to-day needs. Their perception of the individual(s) running in their wards would also factor in their voting decisions. Let's call these "local" issues.
Can we measure the relative importance of "macro" and "local" factors?
Here, I assume different parties represent different macro factors, because each party has a set of policies it wants to push for, together with its own brand or identity.
A cursory look at the data would indicate the important of macro factors. This is because the performance of the different parties was quite varied in the Singapore 2011 General Election. For example, the Workers' Party garnered 48% of votes, on average, in each of the constituencies it entered, while the Reform Party fared 32% on average. So the parties' branding and policies matter.
Performance also varies widely within each Party's wards. For instance, the National Solitary Party won 10 percentage-points more votes in Marine Parade than it did in Jurong. Local factors - which represent everything else from ward-specific issues, demographics, charisma of election candidates etc. - must be at work here.
Let's now do some measurements. First, I measured the strength of macro factors, which as mentioned varies by party. By using a simple regression, I estimated the proportion of votes the People's Action Party (PAP) (the incumbents) would win in each constituency. For example, the PAP would be expected to win 52% votes in each ward challenged by the Workers' Party.
Once these macro factors are fixed, we can derive the influence of local factors. This is done by simply subtracting the actual 2011 GE results from the predicted ones based on macro factors, giving us the strength of local factors. The results are summarised in the table below. On this count, Hong Kah North voters were most in favour of the PAP, with local factors adding 11%-points to the PAP's votes. On the other hand, local factors were against PAP in Hougang and Potong Pasir, traditional opposition strongholds.
Local vs macro: which matters more? On average, macro factors cause votes to vary by 5.7%-points on average. However, micro factors swing the votes by about 5.8%-points on average. The numbers are very close, so it looks like local and macro factors carry equal weight. Building a strong party is important, but it is only the job half done.