Get smart on immunisation: the stats behind the SBS article

Today, an article of mine on immunisation rates in Australia was published on SBS News. It explores the reasons why more educated parents have lower immunisation rates. The charts on the article were designed to be relatively simple to allow them to be digested by the general public.

However, for anyone that is interested in the underlying numbers and relationships, here are a couple of wonkish charts. These charts help to illustrate the relationship between education levels and vaccination rate.

First off, the scatter plot and linear regression function for education levels vs five-year vaccination rates.

The correlation coefficient between the variables is -0.28. Whilst this indicates a weak-ish relationship, I think it is one worth exploring, given that:

• The SA3-level data is the finest-grained data available for immunisation rates. These areas have populations in the range of about 10,000 to 170,000, meaning that the data is very noisy. Most areas will feature both rich and poor residents. SA4 data for immunisation would be great, but is not available publicly.
• This is social science data, therefore the data is inherently fuzzy

The chart above shows the distribution of the count of SA3s at different education levels. This chart is not population weighted. The vaccination rate for each education level is overlaid. This paints a fairly clear picture of how vaccination rates drop as education levels rise.

As an aside, I also create population-weighted charts to take into account the variation in populations seen in SA3s. The results were broadly similar, therefore in the interest of keeping the charts simple, I used the non-population weighted results.

Interactive Australian electoral division map

The map below shows Australian federal electoral divisions and the results from the 2010 election. These electoral divisions provide the basis for seats in the Australian lower house, known as the House of Representatives.

Click on the map below to navigate around the electoral seats. Click on a seat to see more details, and click again to zoom back out.

Please note: this has not been set up for viewing on the mobile version of the blog. Click here to go to the desktop version.

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Name of electoral division  --		Two party result -- --
Party  --    Member  --
Median total family income (weekly)  --
Median mortgage repayment (monthly)  --
Average age  --    Population  --

The results shown are based on the Mackerras pendulum, where each division is assessed on a two party preferred basis, with data taken from the Australian Electoral Commission. This assessment is based on the size of the two party margin and allows each seat to be classified as marginal, fairly safe, safe, very safe or cross bench.

This map has been built using the d3.js framework. The Commonwealth electoral division mapping data was provided by the Australian Bureau of Statistics. The political data is provided by the Australian Electoral Commission.

The Australian election debate: a Twitter event

The televised debate between Kevin Rudd and Tony Abbott increase the amount of Australian election tweets by a factor of about 19. The event, which started at 6:30pm on Sunday 11th August, saw over 50,000 tweets while it was in progress.

As mentioned in my previous post, I collected a lot of tweets during the Australian election debate between Kevin Rudd and Tony Abbott. Although I had expected an increase in the amount of tweets, I didn't expect such a massive increase.

The massive increase in volume of Australian election tweets is shown in the chart above. The chart shows the day of the debate, plus the two preceding days for comparison. Between 6pm and 8pm on the night of the debate, I collected a massive 71,263 Australian election tweets. The same hours on the previous night saw only 3,755 tweets sent - meaning that the debate increased the volume by about 19 times.

A key driver of this engagement was clearly the interactive elements encouraged by the media networks. Most networks, including the ABC, Channel Nine and Channel Ten had their own unique hashtags to allow their viewers to tweet their votes. This form of engagement, straddling both traditional and new media, was clearly effective for the broadcasters.

Rudd vs Abbott debate, minute by minute in Tweets

Towards the end of tonight's Australian election debate between Kevin Rudd and Tony Abbott, I captured almost 2,000 related Twitter tweets per minute, and over 50,000 were captured during the hour. This has provided me with a mountain of data - so first off, let's look at the debate minute-by-minute.

In the chart above, we can see the subjects mentioned in tweets during the debate. The first spike in tweets was about immigration, after about ten minutes of the debate. A much larger spike in activity belonged to the economic discussion, at about 18 minutes.

The economy remained one of the most popular topics of discussion for the rest of the debate, except on three occasions. In the 23rd and 48th minutes, immigration and then the environment briefly overtook the economy as the most tweeted topic.

However, with only four of the sixty minutes remaining, the subject of same-sex marriage suddenly came up. This caused a spike from mere single digits to a massive 676 tweets per minute. This was more than double the maximum number of tweets per minute seen for the economy, immigration and the environment during the debate.

The ABC and Channel Nine each asked their viewers to use hashtags to identify who they thought had won the debate. The above chart tracks the number of tweets with each hashtag per minute.

Until about the tenth minute, it was fairly even. However, it appears that the audience on Twitter started to give Kevin Rudd the edge from that point onward. Rudd's votes continued to trend upwards, peaking at 119 Twitter votes during the 56th minute - the same time as the spike in tweets about same-sex marriage.

Votes for the leader of the opposition, Tony Abbott, peaked at 47 tweets per minute on two occasions during the debate. However, generally his votes plateaued in the low-30s for the latter half of the debate, significantly below the volume of support received by Rudd.

This post was subsequently republished on the SBS News site, with the authorisation of the author.