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Why did women in Chicago stop bicycling to work? And other stories about data

Why did women in Chicago stop bicycling to work?
Or is our data unreliable?

Showing relative cycling-to-work rates between 2005 and 2009 in Chicago. Data from table S0801 in American Community Survey, 1-year estimates. Read the comments on this post for why this is not the best data source – 3-year estimate shows same decline in women cycling to work.

Note: The sample size is puny – data was collected from 80,613 housing units in Illinois. I don’t know how many of those were in Chicago (and we have 1,063,047 housing units). The American Community Survey only collects data on transportation modes to work for ages 16 and up.

But we simply have no other data! Maybe the Chicago Metropolitan Agency for Planning can release the Chicago data they collected for the 2008 household travel survey to show us bicycling rates for all trip purposes (they divided the report into counties). The sample size would still be small, but we could compare the work rates to find some support between the datasets.

We should look into how New York City counts bicycling as an additional way to gauge trends in Chicago (it has limitations of geography and area).

They conduct two types of counts. The first is the screenline count for bridges, Staten Island Ferry, the Hudson River Greenway, and all Avenues at 50th Street. They do this three times per year. Then, seven more times a year, they count at the same places (except the Avenues) from April to October.

While this data does not give them information on who cycles in the boroughs, it does give them a good indicator of cycling levels in Manhattan. It also disregards trip purpose, counting everyone going to work, school, or for social activities.

Sidenote: The New York Police Department will begin making monthly statistical reports on bicycle crashes in the city.

Some disjointed thoughts about bike commuting rates and how we get them

  1. In November 2010, I wrote that Minneapolis and St. Paul, Minnesota, have a higher percentage of workers (16 and older) commuting to work by bicycle.
  2. Yesterday, I updated an article about how the frequency of women in Chicago bicycling to work is decreasing.
  3. Today, I started updating the November Minnesota article to include the 2007-2009 3-year estimates from the American Community Survey (which shows that bicycling to work is growing faster in Minneapolis than Chicago). View the rudimentary spreadsheet. Bottom line: MPLS jumped from 3.55% bike mode share to 4.14% and Chicago only went from 1.04% to 1.13% (but again, only counting employed people!). Can we get some recession job statistics?
  4. Unemployment rate in Minneapolis-St. Paul-Bloomington, MN-WI MSA is 6.5%; Chicago-Joliet-Naperville, IL-IN-WI MSA is 9.0%. See the table on Bureau of Labor Statistics.

But now I must pause and look at what I’m analyzing.

Someone pointed out in the comments on Chicago bicycling (and working) women that the sample size is low and the margin of error high meaning it’s hard to make accurate interpretations of the change in ridership from year to year. He suggested increasing the sample size.

Add this to the fact that the Census Bureau only collects data on trips to WORK and not everywhere else that people go daily. In this recession, fewer people are working. In fact, perhaps women lost their jobs more frequently than men. That could perhaps explain the drop in women bicycling to work. To increase the number of women bicycling to work, perhaps we just need to find more jobs for women. See points 3 and 4 above for evidence on the number of people who bicycle for transportation that we’re not counting.

After thinking these things over, my point is that gauging a city’s ridership based on Census Bureau home to work data is insufficient.

If these Phoenix bike riders aren’t going to work, they aren’t being counted.

To move from a bicycle subculture to a bicycle culture, we’ll need to know when we get there. We need a better picture on who is riding and for what purpose. CMAP rarely performs their household transportation survey (which gathers data on all trips on all modes and in many counties) and when they do, they don’t single out cities. In essence, Chicago doesn’t know where or why people are riding their bicycles (except for the limited and noisy information the Census or American Community Survey provides) – we have no good data!

Both New York City, New York, and Portland, Oregon, methodically perform bicycle counts annually. Both cities also count ridership on their bridges: Portland has at least 5 to count, NYC has over 10 (also called a screenline count). They can report how many people are riding bikes on the street, blind to their trip purpose and destination. It’s easy to note changes in ridership when you count all trips over work trips.

Frequency of Chicago women riding their bikes to work is down

UPDATE: I added data from years 2005-2007 to complement existing 2008-2009 data in Table 1 as well as a visual representation. I have also added data from the 3-year estimates to Table 2.

UPDATE 01/20/11: Added the most recent 3-year estimate that the Census Bureau released in January 2011 to Table 2.

In September 2009, I wrote about “what the Census tells us about bicycle commuting” and a couple of days ago I compared Chicago to Minneapolis and St. Paul.

I want to update readers on the changes between the 1-year estimate data reported in that article (from 2008) and the most recent 1-year estimate data (from 2009). Percentages represent workers in the City of Chicago aged 16 and older riding bicycles to work.

Table 1 – Bicycling to work, 16 and older, 1-year estimates

Year Total MOE Male MOE Female MOE
2005 0.7% +/-0.1 0.9% of 621,537 +/-0.2 0.4% of 541,013 +/-0.1
2006 0.9% +/-0.2 1.2% of 645,903 +/-0.3 0.7% of 563,219 +/-0.2
2007 1.1% +/-0.2 1.4% of 656,288 +/-0.3 0.7% of 574,645 +/-0.2
2008 1.0% +/-0.2 1.5% of 657,101 +/-0.3 0.5% of 603,640 +/-0.2
2009 1.1% +/-0.2 1.8% of 651,394 +/-0.3 0.4% of 620,350 +/-0.1

View graph of Table 1. MOE = margin of error, in percentage points.

We should be concerned about the possible decrease in the percentage of women riding bicycles to work, especially as the population size increased. The margin of error also decreased, thus suggesting an improvement in the accuracy of the data. There have already been many discussions (mine, others) as to why it is important to encourage women to ride bicycles and also what the woman cycling rate tells us about our cities and policies. If the decrease continues we must discover the causes.

But Table 1 doesn’t tell the full story.

As Matt points out in the comments below, the number of surveys returned for 1-year estimates is smaller than that from the Decennial Census. Therefore, I took a look at the two 3-year estimates available, each having a larger sample size than the 1-year estimates (see Table 2). The data below seem to show the opposite change than seen in Table 1: that the number of women bicycling to work has increased. The crux of our quandary is sample size. The sample size is the number of people who are asked, “How did this person usually get to work LAST WEEK?”

Table 2 – Bicycling to work, 16 and older, 3-year estimates

Click header for data source 2005-2007 2006-2008 2007-2009
Total workers 1,203,063 1,230,809 (+2.31%) 1,291,709 (+4.71%)
Males bicycling to work 7,549 9,014 (+19.41%) 11,014 (+18.16%)
Females bicycling to work 3,474 3,741 (+7.69%) 3,542 (-5.62%)

The number of discrete females who bike to work has decreased in the most recent survey (2007-2009) while the total number of workers 16 and older has increased, giving females bicycling to work a smaller share than the previous survey (2006-2008). We must be careful to also note the margin of error for females bicycling to work is ±499.

Matt suggested that sustainable transportation advocates “push for higher sampling” to reduce “data noise” and increase the accuracy of how this data represents actual conditions. I agree – I’d also like more data on all trips, and not just those made to go to work. Household travel surveys attempt to reveal more information about a region’s transportation.

One of the two overall goals of the Bike 2015 Plan is “to increase bicycle use, so that 5 percent of all trips less than five miles are by bicycle.” Unfortunately, the Plan doesn’t provide baseline data for this metric, but we can make some inferences (there will probably be no data for this in 2015, either). The CMAP Household Travel Survey summary from 2008 says that the mean trip distance (for all trips) for Cook County households is 4.38 miles (under five miles). The same survey says that for all trips, 1.3% were taken by bike. These can be our metrics. *See below for men/women breakdown. Note that no data for “all trips” exists for the City of Chicago.

We will not achieve the Bike 2015 Plan goal unless we do something about the conditions that promote and increase bicycling. Achieving the goals in the Bike 2015 Plan is not one group or agency’s responsibility. The Plan should be seen as a manifestation of what can and should be done for bicycling in Chicago and we all have a duty to promote its objectives.

Please leave a comment below for why you think the rate of women who bike to work has stayed flat and decreased, or what you think we can do to change this. Does it have to do with the urban environment, or are the reasons closer to home?

*The same survey also said: Cook County males used the bike for 1.9% of all trips. Cook County females used the bike for 0.8% of all trips.

Table 1 data comes from the 1-year estimates from the American Community survey, table S0801, Commuting Characteristics by Sex for the City of Chicago (permalink), which is a summary table of data in table B08006. Table 2 data directly from American Community Survey table B08006.

The woman or family side of bicycle planning

Recently after I posted the American Community Survey findings on bicycle commuting rates in Chicago and the United States (which both show a gap between male and female cycling to work rates), Let’s Go Ride Bike posts an entry about the media’s analysis of the cycling gender gap. I didn’t posit any thoughts about the gap I noticed in the blog entry I wrote.

I recommend you read what Dottie wrote, which includes ideas about how to get more women to ride their bikes outside of the recreation arena. Her influence to write the article came from three recent articles from larger media sources (NYT, TreeHugger, Scientific American).

Will protected bikeways leading to urban shopping and school destinations be the trick? Or should we step up targeted education? Is it the bike? Sweating? Fashion? How should families on bikes play a role in bicycle planning?

I’ll take this research and writing into consideration as I develop a new perspective on how I can convince my mom to ride her bike the two miles to work at least one day per week in good weather (she currently drives between home and work in Salt Lake City).

I visited her in May and drove her to work one morning. I noticed very low traffic and several other commuters traveling by bicycle that could keep her company. I want her to take a class on urban bicycling at the Salt Lake City Bicycle Collective, but their website’s helpfulness only goes so far and no one’s answered my email.

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