Monday, 23 November 2009

The trouble with statistics !

A recent article in Tree Hugger celebrated the increase in the number of people cycling in New York City. Based on counts at 6 key NYC locations,  there has been a 26% increase in the number of commuter cyclists in 2009. This comes on top of a 35% increase in cycling levels in 2008. Overall, this represents a 66% increase in the recorded number of people cycling in the last 2 years.

By comparison, a recent report "Cycling as a Mode of Transport in Manchester" to the Communities and Neighbourhoods Overview and Scrutiny Committee announced that "recorded cycling levels into the City Centre have shown an increase of 59% since 2005"

Although this increase was over a longer time period (5 years) than in New York City, and clearly not all the local councillors on the scrutiny committee seemed that enamoured with people on bicycles (in some cases hostile is probably a more accurate description), these increases certainly sound impressive and are to be welcomed.

But as is often the case with headline statistics, it is necessary to dig a little deeper to get a clearer picture.  In the case of Manchester, the percentage increase figure is totally correct but there is no context to what it actually means.

To get some context, you will need to delve into another report - the intriguingly titled "Manchester LPSA2 Modal Share Surveys. Report of Results. GMTU Report 1523  June 2009".  Unfortunately not yet available via the web.

This report gives the modal share data for recorded trips into the City Centre in 2005 and 2009 and reveals that cycling's modal share increased from 0.7% in 2005 to 1.1% in 2009.  Yes, there was a 59% increase in the number of recorded trips made by bicycle, but this represents an increase from a very, very low baseline to a still very low baseline when compared to European cities such as Gronigen and Copenhagen which achieve average figures of 40-45% (or higher) of all trips within the City Centres being made by bicycle.

If Manchester wants to meet its recently announced bold C02 emission reduction targets (1) as well as tackle other key challenges including health (obesity), air quality management (vehicle pollution), congestion and social exclusion then it clearly needs to massively up its game and make Manchester into a cycling city.

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