Hannah Williams :)

ideas. design. open data. social change.

How many locals share your birthday?

This playful infographic represents the number of local birthdays celebrated each day of the year. Each circle represents a day of the year and its size is determined by the number of birthdays occuring on that day. Colour is used to represent probable dates of conception, with warmer colours showing high numbers of probable conception and cooler colours lower numbers. Created as Black hat and Nimbus with Mark Henning.

Scroll down for a detailed description of the artwork and some observations.


Data Visualisation Public Art
Woodbridge Island

Birthdays are a fairly universal day of celebration, transcending cultural differences. Commuters can satisfy their natural curiosity and see how many people in the area share a birthday with them, or see how many people are celebrating a birthday today. This provides commuters with a point of interaction with the area and communities they are moving through.

The design direction was inspired by old lucky packets we remember often getting at friends’ birthday parties as kids, and the bright colours and circles result in an appropriately cheerful, lighthearted and friendly visual. White outlines on the circles give a little extra visual impact and make it easier to compare the sizes of the circles.


Some Observations

The data that exists for birthdates (from the 2001 census) is on ward level, so what is shown here is the birthdays for the suburbs of Ward 55, which includes:

Tygerhof, Sanddrift, Woodbridge Island, Milnerton Central Metro Industrial , Ysterplaat, Rugby, Paarden Eiland, Woodstock, Brooklyn, Salt River, Ysterplaat Air Base, Lagoon Beach, Milnerton Golf Course, Maitland, West Side Of Residential Area Of Century City, Waterfront Area , Sunset Links and, oddly enough, the Prince Edward Islands almost 1800km off the coast of South Africa in the sub-Antarctic Indian Ocean (although as a nature conservation area these are uninhabited apart from researchers and conservationists).

It’s interesting to note that the most common birthdays are January 1st and October 10th, but this is slightly misleading as many people who do not know their birth date filled in either January 1st or the date of the census which was October 10th. Apart from these dates the 6th June is the most common birthday, but being the 6th of the 6th it would also be a convenient date to choose if you weren’t sure of your birth date. If you ignore these, the most common birthday is the 10th February.

The least common birthday in the area is March 30th (apart from February 29th), followed by March 7th.

The most common probable date of conception is May 25th. Dates like Valentine ’s Day and new years have average numbers of probable conceptions.