More on soda taxes

A few days ago, the World Health Organization (WHO) came out with report, suggesting the use of food taxes and subsidies to encourage healthy eating.  They were particularly in favor of soda taxes.  Soda taxes seems to be picking up steam in the U.S..  After passage in Berkeley, they will now be on the ballot in several locales in coming weeks.  

I've written so much on these topics, it's hard to know what more to say.  So, I thought I'd just, for the record, tell you what I had to say on a recent Food Sommelier podcast when the host asked me about this topic (and revealed her support for soda taxes, which came about in part because she said she felt guilty for having worked for PepsiCo earlier in her career).  

I'm in episode 38 and the discussion on soda taxes starts at about the 20 minute mark.  Here is my lightly edited discussion on the issue. 

“I’m not a fan of soda taxes for a whole host of reasons . . . but let me first say, though, that it’s really not that big a deal.  And that’s probably one of the reasons I’m against it . . .  As much as I’ve written about it, you’d think I’d get my feathers ruffled a lot [over things like the Philadelphia soda tax], but I don’t have a dog in the fight really one way or the other.  It’s not a big deal in the sense that, number 1, it’s just not going to have much of an effect on obesity rates if you look at the best available research.  We are talking about taxes that will have very, very small effects on people’s weight, and there a lot of reasons for that.  

There are substitutes for sugar sweetened beverages.  People can switch to juices or even non-beverage alternatives that may have calories in them.  I’ve seen a number of studies that suggest that.  Just because we put a tax on something doesn’t mean people are not going to consume calories; they might instead switch to something else equally caloric.  . . . 

We have these intuitions . . . and little thumb rules like for every 3,500 kcal we cut out, we lose a pound.  The reality is that relationship is not linear at all.  It’s nonlinear . . .  When we’re thinking in a linear way, each calorie I cut out will cause a constant reduction in weight, but it doesn’t really happen that way.  There are diminishing returns.  You may lose a little bit initially but then it will really level off.  . . .

When you look at the burden of the tax, and this is really true of almost any food tax, its going to tend to be borne relatively (at least relative to income) more by people in the lower economic strata of society.  The reason for that is that if you look at the share of spending on food, it tends to go down as we make more money.  What that means is that poor people are spending a larger proportion of their income on food. So, anything we do to make food more expensive, that burden or that tax, is going to tend to fall more heavily on lower income populations. . . .

I’ve got a paper actually coming out . . . where we compare very low income to regular income consumers.  What we tended to find there is that is that, especially in the case of subsidizing healthy foods, the richer consumers benefit the most because they’re already, first of all, consuming relatively health foods.  And, because we found . . . that the poor tended to want to stick to their original diets. They were more habit prone, so they didn’t change quite as much either when it was a tax . . . or a subsidy trying to get them to eat something a little healthier.  

I would say lastly, I’m going to bring up this sort of elitism. . . . This sort of paternalism argument.  We feel like we know how other people should be eating.  . . . I think it’s really hard to put ourselves in the shoes of other people, and so for us to take a step back and say ‘you should be doing something different; you should be eating more like me’ presumes that we know what it’s like to have their life and have their kind of income and know all the other sorts of things they’re facing. . . .  I have a problem philosophically with that. . . .

And I do think it’s different than . . . cigarette taxes.  With cigarette taxes there really was this externality – the second hand smoke.  When you’re smoking, that really does have an effect on the people around you.  With the drinking of soda, it’s really less clear there’s that same kind of phenomenon at play.  Most of what’s happening here is some kind of redistribution within our healthcare system because of Medicare and Medicaid.  But, that’s much more complicated than most people realize.  Most of what’s happening here are subsidies flowing from relatively wealthy people to relatively poor people because relatively wealthy people pay more in taxes. . . . It’s not a popular solution but part of the argument is that if people know their health care expenses are going to be taken care of, they’re going to eat in an unhealthy way . . . Economists call that a moral hazard.  The answer for a moral hazard is that people need to have some skin in the game.  We need people to pay a little bit of the costs of their health care.  It doesn’t have to be the same for everybody, and maybe it’s just a small amount for people who don’t have much income, but I think if the concern is that if people are going to behave “irresponsibly”, there needs to be a bit of a price for that in terms of their health care costs.  But, of course, there is a real price for being obese.  That’s something we tend to forget – that there is a lot of social shame associated with being obese, wages can be lower especially for women, and there are all the attendant medical costs, some of which are shielded from the consumer because of our health care system but a lot of those are borne directly.  There is a real cost to being overweight and obese, and people bear a lot of that just through their own daily lives.  

I’m running on here, but one last point that is really important because I hear so many people get this wrong.  What they say is, ‘well our farm policy system subsidizes food and makes sugar cheaper.’  That is absolutely false.  I’m not a fan of farm subsidies, but that particular argument is false for two reasons.  One is that if you look at cane sugar.  Cane sugar has a set of really convoluted policies, but they essentially restrict supply. . . . What [sugar producers via policy] are able to do is keep out foreign competition and keep other producers from growing sugar cane.  . . . World sugar prices are much higher than they would be if we didn’t have our US cane sugar policies.  The other thing is high fructose corn syrup (HFCS).  Right now roughly 40% of our corn supply goes to ethanol.  Ten years ago, that was mostly going to livestock and food processing. . . .  It’s not exactly a farm policy, but the energy policies we’ve had over the past 10-20 years have dramatically shifted corn production from going to places like HFCS to instead ethanol production and our cars, and as a result has made HFCS more expensive than it would be otherwise.  

Should we tax sugar?  In some ways, we already do, it’s just not very transparent that we’re doing it."                                       

Food Spending

A colleague sent me a couple articles highlighting recent trends in spending on food at home and away from home.  Here's Ashley Lutz at Business Insider from back in July:  

“Restaurant sales growth has stalled in America.

McDonald’s, which had previously executed a huge turnaround, saw a slowdown in the most recent quarter. Other chains ranging from Chipotle to Buffalo Wild Wings also reported sales declines. ”

And, here's a story from a couple days ago by Bob Bryan also at Business Insider:

“Fast-food chains have watched their sales growth drop off a cliff.

Executives advance plenty of reasons for the slowdown — or, in the case of some brands, the outright decline in sales. Some blame politics, others blame the oil crash, and so on.

The real reason may be a bit simpler: It’s getting cheaper for Americans to eat at home.

The price of food at grocery stores has actually been on the decline since the end of 2015, based on the Consumer Price Index for food at home. In fact, in July (the most recent data available), the cost of food at home declined 1.55% from the same month a year ago.

On the other hand, the cost of food away from home — what you pay at restaurants — is still on the rise. In July, prices for food away from home rose 2.79% from same month last year.”

I thought I'd track down the numbers myself and see what's going on.  Here is the CPI data from the BLS, confirming the decline in prices of food at home and the increase in prices of food away from home.

The difference in trends looks even more dramatic if plotted in relative terms.  Here is the CPI for food at home divided by the CPI for food away from home.  Clearly, food at home has become relatively cheaper (compared to food away from home) over the past year.  

If the price of food at home is falling compared to the price of food away from home, does that that mean consumers are spending less on food at home or away from home?  Not necessarily.  Lower prices for food at home will induce consumers to buy more food at home.  Whether they ultimately spend more or less on food at home depends on the magnitude of the own-price elasticity of demand for food at home, and the cross-price elasticities of demand for food at home and away from home (I've previously estimated these parameters as discussed here).  

My data suggests these relative price changes have had a more complicated impact on food spending than suggested by the Business Insider articles.  Here is data from my monthly Food Demand Survey (FooDS) on estimated weekly food spending.  Interestingly, it appears there is a bit of an upward trend in spending on food away from home (spending on food away from home has increased 22% since January 2016), but by contrast spending on food at home has remained relatively more stable (spending is only 0.8% higher than in January, although it is about 5% higher than it was in June).  Thus, the increase in the relative price of food away from home hasn't led to a big drop off in spending on food away from home.  

As a consequence of the above trends, the share of food spending directed toward food away from home has risen from about 0.34 at the first of the year to about 0.38 today, as shown in the graph below.

All this might seem a bit counter-intuitive.  Prices on food at home fall, and yet people spend a smaller share of their food dollar on food at home.  Why?  The answer is because: spending = price paid * quantity purchased, and the two variables on the right hand side of the equation tend to work in opposite directions of each other.  When prices are lower, people tend to buy more quantity.  Whether the effect of changing prices has a bigger effect on spending than the effect of changing quantities, again, depends on the underlying demand elasticities.    

Real World Demand Curves

On a recent flight, I listened to the latest Freakonomics podcast in which Stephen Dubner interviewed the University of Chicago economist Steven Levitt about some of his latest research.  The podcast is mainly about how Levitt creatively estimated demand for Uber and then used the demand estimates to calculate the benefits we consumers derive from the new ride sharing service.  

Levitt made some pretty strong statements at the beginning of the podcast that I just couldn't let slide.  He said the following:

“And I looked around, and I realized that nobody ever had really actually estimated a demand curve. Obviously, we know what they are. We know how to put them on a board, but I literally could not find a good example where we could put it in a box in our textbook to say, “This is what a demand curve really looks like in the real world,” because someone went out and found it.”

As someone whose spent the better part of his professional career estimating consumer demand curves, I was a bit surprised to hear Levitt claim "nobody ever had really estimated a demand curve."  He also said, "we completely and totally understand what a demand curve is, but we’ve never seen one."  The implication seems to be that Levitt is the first economist to produce a real world estimate of a demand curve.  That's sheer baloney.  

The most recent Nobel prize winner in economics, Angus Deaton, is perhaps most well known for his work on estimating consumer demand curves.

In fact, agricultural economists were among the first people to estimate real world demand curves (see this historical account I coauthored a few years ago).  Here is a screenshot of a figure out of a paper by Schultz in the Journal of Farm Economics in 1924 who estimated demand for beef.  Yes - in 1924!  I'm pretty sure that figure was hand drawn!

Or, here's Working in a paper in the Quarterly Journal of Economics in 1925 estimating demand for potatoes.

Two years later in 1927, Working's brother was perhaps the first to discuss "endogeneity" in demand (how do we know we're observing a demand curve and not a supply curve?), an insight that had a big influence on future empirical work.

Fast forward to today and there are literally thousands of studies that have estimated consumer demand curves.  The USDA ERS even has a database which, in their words,  "contains a collection of demand elasticities-expenditure, income, own price, and cross price-for a range of commodities and food products for over 100 countries."   

Here is a figure from one of my papers, where the demand curve is cleanly identified because we experimentally varied prices.  

And, of course, I've been doing a survey every month for over three years where we estimate demand curves for various food items.

In summary, I haven't the slightest idea what Levitt is talking about.  

Food Insecurity is Down

The USDA just released their annual accounting of food security in the United States.  Good news!  Food insecurity fell to 12.7% in 2015 (down from 14.9% in 2011).  Here's a key graph from the report.

One could quibble with the USDA's method of computing food security (it is based on  responses to a variety of survey questions), but whatever "flaws" are inherent in the USDA methods, as long as they have remained constant over time, the trends should be informative.  

Of interest is how food insecurity measures change with participation in SNAP (aka "food stamps).  Using USDA data on SNAP participation, I calculated per-capita participation which is shown in the following graph.  Though the pattern is somewhat similar (i.e., food insecurity and SNAP participation both rose after the Great Recession and then declined in 2015), it isn't a perfect corollary.  In particular, food insecurity is higher in 2015 than in was in 1995, but today there are more participants per capita on SNAP than there were in 1995.  

Another variable which might relate to food insecurity and SNAP participation is the price of food.  Here is a graph of Bureau of Labor Statistics data showing the price (or CPI) of food relative to the price (or CPI) of non-food items from 1995 to 2015.  

Over at the US Food Policy blog, Parke Wilde notes that even though food insecurity has fallen, it hasn't fallen nearly enough to keep up with food insecurity targets.  The above graphs suggest one potential reason why: food is relatively more expensive today than was the case 20 years ago.  Of course, the overall story is surely much more complicated than that.  

Optimal fat tax

In the Washington Post article Catherine Rampell raises an important point with regard to the emerging debate over whether to tax soda.  

“Instead of arbitrarily singling out one category of bad foodstuff for taxation — and the categories of bad foodstuffs will always be somewhat arbitrary — a more effective route to reducing consumption of excessive sugar or calories might be a universal, graduated sugar or calorie tax.

But even that still doesn’t quite seem fair or, for that matter, efficient. After all, a calorie tax would also hit people who consume more calories because they are very active, such as marathoners. Besides being regressive, a tax on calories or sugar would also effectively, if unintentionally, make it more expensive for trim people to exercise.

In other words, a lot of inputs go into determining whether a person is obese. Taxing some of those inputs distorts the relative prices of those inputs, but it doesn’t necessarily change the desired output: obesity rates.

Which raises the question: Why not just target the output, rather than some random subset of inputs? We could tax obesity if we wanted to. Or if we want to seem less punitive, we could award tax credits to obese people who lose weight. A tax directly pegged to reduced obesity would certainly be a much more efficient way to achieve the stated policy goal of reducing obesity.”

Yet, people don't seem to like the idea of a fat-person tax.  Why not?

“Maybe it’s because they’re regressive (but so are soda taxes). Maybe it’s because it sounds like we’re shaming fat people (but arguably so does any policy aimed at reducing obesity). Maybe it just feels unfair to tax people based in any way on their genes, which, like diet and exercise, can also be a determinant of weight.

But if we assume it’s impossible for obese people to lose weight by any combination of inputs they do have control over, it’s hard to simultaneously argue that making one of those inputs more expensive could lead to some nationwide weight-loss miracle. Pop goes the pop-tax rationale.”