2012 ACS non-motorized mode share estimates

The American Community Survey (ACS) 2012 1-year estimates were released recently, and the Star Tribune ran a piece titled ‘Minneapolis sees surge in residents choosing to walk or bike to work’.

More than 11 percent of the city’s residents opted for one of the two nonmotorized options in 2012, the Census Bureau’s American community Survey found. That’s a nearly 25 percent increase from the 9.2 percent who walked or biked in 2011.

[...]

In 2012, 6.9 percent chose walking to work and another 4.5 percent pedaled, according to the survey. In 2011, those percentages were 5.8 walking and 3.4 biking.

I have been written before about difficulties in making grandiose statements about mode share.  It is important to keep these numbers in context. It is a fact that the ACS estimated non-motorized mode split in Minneapolis rose 24.9 percent since the 2011 estimate, however, the same survey indicates that the non-motorized mode split fell 9.8% in 2011, 1% in 2010, and 1% in 2009.

I don’t want to be misunderstood: The data clearly suggests an increasing trend since the first ACS results were released in 2005, however, a headline suggesting there was a 25% “surge” in a single year is misleading. There is a lot of noise in the data, and the margin of error on the ACS estimates is usually somewhere around 1% as well.

Anyway, I’ll let statisticians weigh in on the reliability of the data itself, I mostly just wanted to present the same data in context with all the similar data collected since 2005. Just for fun, I’ve also shown the estimates by gender as well.

Minneapolis Commute Walking Mode Share

Minneapolis Commute Walking Mode Share

Minneapolis Commute Biking Mode Share

Minneapolis Commute Biking Mode Share

I was also curious to see the estimates for Saint Paul. Using the same reporting methodology as the Star Tribune article, the 2012 estimate for walking and biking combined increased from 5.3% to 5.4%, an increase of 1.9%.

Saint Paul Commute Biking Mode Share

Saint Paul Commute Biking Mode Share

Saint Paul Commute Walking Mode Share

Saint Paul Commute Walking Mode Share

And to save everyone the trouble of trying to compare Minneapolis and Saint Paul in the charts above, here’s the same info with the two cities on the same chart.

Saint Paul & Minneapolis Commute Mode Share Comparison

Saint Paul & Minneapolis Commute Mode Share Comparison

I’ll let others draw conclusions in the comments below or in future posts. What are your thoughts about the 2012 ACS non-motorized mode share estimates?


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4 Responses to 2012 ACS non-motorized mode share estimates

  1. Walker Angell
    Walker Angell September 21, 2013 at 9:12 am #

    Great post Reuben. You’re exactly right, I think in any surveys like this you have to always be very careful about exact numbers, particularly year to year. The value is in being able to see trends, especially over the longer term. So long as the polling methodology is the same, running averages (3 year might be good here?) should at least give you an indication of stable up or down trend over time—bicycling and walking are increasing, decreasing, or staying the same. Between the two survey’s you posted there’s clearly an up trend. That’s good.

  2. melanie September 21, 2013 at 9:20 am #

    Interesting. I wonder if you overlayed average gas prices if you would see any correlations.

  3. Bill Lindeke
    Bill Lindeke September 22, 2013 at 10:30 am #

    this year, I was a data point in St Paul. I’d just moved to my new apartment last August. Nobody even knew my new address. But then I got a knock on the door one afternoon. It was the ACS guy, and I gleefully told him all about my bike commuting.

  4. Gary September 24, 2013 at 5:14 pm #

    Up until I moved to St Paul I rode my bike everyday, year round and commuted daily to work for over 20 years. I consider myself the most hardcore of hardcore cyclists but honestly I have become so frustrated by the complete lack of cycling infrastructure and amenities in St paul that I actually quit riding altogether. I just run now and ride my bike at home on the trainer. The lack of bike lanes, sharrows, cycle tracks and bike racks is just tragic in St Paul. Statistically speaking, I am one less cyclist in St Paul.