A Day in the Life: Examining US Birth Rates

Posted by

There are many data initiatives in the Tableau community, and I like to participate in them when I have time.  As a professional in healthcare, one of my favorites is #projectHealthViz.  Each month, Lindsay Betzendahl posts health-related data and invites the community to take a crack at visualizing it.  The December data set ended up sparking a very interesting data journey for me, and I thought it might be useful to share the thought process I went through on this project.

The data
After downloading the data, our first step is to look at the data in Excel.  This lets us get a sense of how the data is structured, and helps us start thinking about how to analyze the data.  Here is a small sample of the data, to give a sense of how it looks:

1 excel grid

This particular data set happens to be nicely structured and fairly straightforward, with one row of data per day.  No real data cleanup is needed, so on to Tableau!

Getting a sense of the story
Next, let’s pull the data into Tableau and do some quick prep work.  After combining year, month, and date_of_month into one Date field, let’s plot the total births per year to see the basic shape of the data:

2 basic trend

This isn’t very interesting, but there’s a somewhat intriguing bump in the middle.  Let’s investigate by zooming in on the y-axis:

3 zoom trend

This is much more interesting.  What happened in 2008 that caused such a huge drop in births?  After some quick searching on Wikipedia et al, I remembered the 2008 Recession!  I bet that had something to do with it…

Bringing in more data
My brother works in finance, and we’ve definitely geeked out over data on multiple occasions.  I remember him telling me about FRED, so that seemed like a good place to start looking.  Sure enough, there is yearly GDP data on FRED.  Pulling it into Tableau and plotting by year, we get the following:

4 gdp

While there isn’t as big of a drop as there was in births, there is definitely an inflection point in 2007.  Let’s see how they look when we compare them directly:

5 combo 1

Okay, so it’s not an immediately obvious correlation, but it looks promising.  Let’s dig a little deeper.  What if we looked at the yearly percent change?

6 percent dif

This actually looks pretty good!  At this point, I started to realize that birth rate is a bit of a lagging measure.  In fact, on average it lags by about 40 weeks, or 9 months.  How do things look if we adjust for time of pregnancy?

7 conception date

This is starting to look like a really compelling association!

Final product
At this point, let’s add some finishing touches, and create our end product:

98 final product.png

I’ve recently been adding very light color to the background of my visualizations.  I generally prefer a light background, but find a touch of color makes it less stark, and easier on the eyes.  Also, as a relatively new parent, I know how expensive kids can be, so I had a little fun with the title.  See the interactive (and downloadable) dashboard here.

Gratuitous stats
To satisfy our statistical side, let’s do a quick check of the Pearson Correlation Coefficient, to see how strong the correlation actually is.  To do this, we can make a scatter plot comparing yearly percent change in GDP and in birth rate, with a circle for each year:

99 pearson

The Pearson Coefficient ends up being 0.8453, which is a fairly strong correlation.

While I never would have thought about the relationship between birth rate and GDP, it does make sense, as you’re probably less likely to have a kid if you lose your job.  That said, there are many possible interpretations.  For instance, my co-author Jorge mentioned that when the US GDP slowed down, there were changes to immigration and emigration patterns that reduced the foreign-born population in the US, which could certainly impact the birth rate as well (related paper).

All in all, I had a great time looking into this data set, and really enjoyed the opportunity to contribute to the conversation in the community.  I hope this glimpse into my thought process is useful, or at least interesting.

Until next time, stay warm out there!



Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.