Friday, December 9, 2016

Unpleasant reversal

In preliminary mortality data out this month from CDC, a few issues stand out. First, estimated life expectancy at birth decreased (by 0.1 year) between 2014 and 2015. Granted, a single year does not a trend make, but some of the underlying details are downright disturbing:

Infant Mortality Rate by Cause:
Source: CDC

Sunday, October 30, 2016

Halloween Fun

Happy Halloween!

Normal Distribution vs. Paranormal Distribution
Source: Journal of Epidemiology and Community Health

A BOOming INDUSTRY:

There were an estimated 41.1 million potential trick-or-treaters (children age 5-14*) in the United States in 2015, roughly the same as in 2014.

But Halloween is clearly not just a children's holiday. 171 million Americans of all ages will be celebrating Halloween this year (up nearly 10% from last year), with total spending reaching more than $8.4 billion.

The average American adult will spend $83 on decorations, costumes and candy, up considerably from $74 last year, and above the previous peak of $80 per person in 2012.

For those who will dress up to celebrate the holiday:
The most popular children's costume: Superhero! (knocking princess from the top spot after an 11-year reign).

Sources: National Retail Federation and U.S. Census Bureau, Facts for Features
*Note: Of course, many other children - older than 14, and younger than 5 - also go trick-or-treating.

TERRIFYING TREATS:

America's candy consumption in 2010 was nearly 25 pounds per person. If this candy were entirely Snickers bars, it would be the equivalent of nearly 4 candy bars, per week, per person. The volume of candy consumed, much like home prices, peaked in the middle of the decade, dipped at the start of the recession in 2008, and increased slowly each year since then. Another scary fact is that 2010 is the last year for which we'll have this data. Budget cuts led to the termination of the Current Industrial Reporting program.

American confectionery manufacturers produce about 35 million pounds of candy corn each year. That adds up to 9 billion candy corns - or about 30 kernels per person in the U.S.

For Halloween itself, Americans purchase nearly 600 million pounds of candy, spending nearly $2.6 billion for treats to hand out to trick-or-treaters.

Sources: U.S. Census Bureau, Current Industrial Reports, Confectionery: 2010National Confectioners AssociationDaily Infographic 2011 and 2012

Friday, June 3, 2016

2015 data show historic low teen births, rising birth rate at older ages

Highlights from the preliminary 2015 birth data

Teen and early 20-something births are at (another) all-time low in the U.S., and birth rates continue to rise at ages 30 and older.

As a historical demographer, who has some experience with fertility and mortality rate trends over the past century (and the century before), and I can say with conviction that the trend is not really new. Birth rates for women ages 35 and older are not higher now than ever. They're not even higher now than they were in the 1950s and 1960s.

The National Vital Statistics Reports, published by the U.S. Centers for Disease Control and Prevention, provide historical birth rate data by age of mother as far back as 1970. Earlier data must be compiled from a variety of other sources including the older, and often PDF-scan-only Monthly Vital Statistics Reports and the U.S. Statistical Abstract.

From those sources I collected data as far back as 1920, with complete annual data from 1935-present. The historical birth rates (births per 1,000 women) are shown in the chart below.



Zeroing in on ages 35 and older, to show more detail on the chart scale, we see that birth rates are indeed higher in 2015 than they were in 1970. But we do not need to go back very much farther to find a time at which birth rates were higher than they are today: In the 1960s birth rates were higher for all ages 35-49 than they were in 2015.

If we go as far back as 1920, birth rates were nearly five times higher for women ages 45-49 than in 2015, nearly three times higher for ages 40-44, and fifty percent higher for ages 35-39 than they are at present.

In short, the phenomenon of increasing birth rates for women in their 30s and 40s is as much a return to historical patterns as a deviation from them.

To be clear, some pregnancy risks do increase with advanced maternal age:
"older age strongly increases a woman's chances of at least three untoward outcomes—namely, stillbirth, miscarriage, and ectopic pregnancy" (Stein and Susser 2000)
However, there is considerable evidence that socio-economic factors play the most important role in birth outcome - perhaps far outweighing the age effects (Cohen 2012, Azimi and Lotfi 2011, Stein and Susser 2000).

As for the current focus on trends in the past four decades, I suspect the ease of collecting data from 1970-present is partly the cause of the focus on a "huge" increase in childbearing at older ages... when, in reality, rates have fallen if you look back just 5 years more.

I am happy to share the raw data upon request. Feel free to contact me for more information.

Wednesday, June 1, 2016

Demography of the 2016 Hurricane Season

The 2016 north Atlantic hurricane season has begun...

The coastline from Texas to North Carolina is most at risk of a hurricane, and in those states, the population of coastal counties is 27 million.

Hurricanes occasionally strike farther north, but despite hurricane Sandy's damage in 2012, such events are considerably less common than hurricanes in the southern states. Yet that does not make the damage any less catastropic. Early estimates place the damage from Hurricane Sandy at about 400,000 housing units damaged or destroyed, the majority of which were in New York (more than 300,000), New Jersey (approximately 70,000), and Connecticut (approximately 3,000).

While Sandy was more recent, and turned the lights off for more people, hurricane Katrina left more fatalities and damaged homes in her wake.

The Department of Housing and Urban Development estimates that in the summer of 2005 hurricanes Katrina, Rita, and Wilma damaged "more than one million housing units across five states." Of the damaged homes 515,000 were in Louisiana, 220,000 in Mississippi, and nearly 140,000 in Texas.

A full five years later, nearly 15 percent of the properties still had substantial visible repair needs, and 11 percent no longer contained a permanent residential structure. In other words, more than one quarter of the homes damaged in the 2005 hurricane season were either completely lost or were still in need of repair five years later.

State of Preparedness
While more than 80 percent of homes in the U.S. have a food supply sufficient for at least 3 days, only about half have a water supply in the event of an emergency.

Mapping Tools
The Bureau of Labor statistics now has an online hurricane mapper tool that provides wage,employment, and establishment data for potential flood zones.
Info at:
http://www.bls.gov/cew/hurricane_zones/home.htm

Friday, May 20, 2016

Milestone

Thanks to Nathan Yau of Flowing Data and Carolina Demography's Twitter, I learned this morning that I've passed a milestone I hadn't thought of. I'm older than half the population in the U.S.

Friday, April 8, 2016

Update: Births to "Older" Mothers Still Not News

This is an update of a post that originally appeared here in February 2013.

Sometimes "common knowledge" is not knowledge at all...

There has been considerable hand-wringing in the press over births to women over the age of 35. According to the Telegraph, older mothers are "driving up the birth defect rate." The New Republic suggests that older parents will "upend American society." And Slate, generally progressive, bemoans the "feminist fertility myth."

As a demographer, I am aware that birth rates in age groups 35-39, 40-44, and 45+ have been rising since the late 1970s for ages 35-39 and 45+, and since the early 1980s for the 40-44 set.

But as the granddaughter of a woman who birthed her youngest child when she was nearly forty, my skeptic antennae went up. My grandmother may have been a singular woman, but she was hardly a statistical aberration.

As a historical demographer, who has some experience with fertility and mortality rate trends over the past century (and the century before), and I can say with conviction that the trend is not really new. Birth rates for women ages 35 and older are not higher now than ever. They're not even higher now than they were in the 1950s and 1960s.



The National Vital Statistics Reports, published by the U.S. Centers for Disease Control and Prevention, provide historical birth rate data by age of mother as far back as 1970. Earlier data must be compiled from a variety of other sources including the older, and often PDF-scan-only Monthly Vital Statistics Reports and the U.S. Statistical Abstract.

From those sources I collected data as far back as 1920, with complete annual data from 1935-2010 (the most recent year for which complete data are available). The historical birth rates (births per 1,000 women) are shown in the chart below.

Zeroing in on ages 35 and older, to show more detail on the chart scale, we see that birth rates are indeed higher in 2010 than they were in 1970. Specifically, birth rates are 45% higher for ages 35-39, 26% higher for 40-44, and 40% higher for ages 45-49 in 2010 than in 1970.

But we do not need to go back very much farther to find a time at which birth rates were higher than they are today: In 1965 birth rates were higher for all ages 35-49 than they were in 2010.

If we go as far back as 1920, birth rates were nearly twice as high for ages 35-39, were three times higher for 40-44 year olds, and were more than 5 times higher for ages 45-49 than the rates in 2010.

In short, the phenomenon of increasing birth rates for women in their late 30s and 40s is as much a return to historical patterns as a deviation from them.

To be clear, some pregnancy risks do increase with advanced maternal age:
"older age strongly increases a woman's chances of at least three untoward outcomes—namely, stillbirth, miscarriage, and ectopic pregnancy" (Stein and Susser 2000)
However, there is considerable evidence that socio-economic factors play the most important role in birth outcome - perhaps far outweighing the age effects (Cohen 2012, Azimi and Lotfi 2011, Stein and Susser 2000).

As for the current focus on trends in the past four decades, I suspect the ease of collecting data from 1970-present is partly the cause of the focus on a "huge" increase in childbearing at older ages... when, in reality, rates have fallen if you look back just 5 years more.

I am happy to share the raw data upon request. Feel free to contact me for more information.