Managing Sewage Demand and Holiday Demand

When it rains it pours – that is, sewage overflows into streams, rivers and lakes and then into our beaches and drinking water (yuck!).   (NY Times 11/22/09)  For example, cases of serious diarrhea at one Milwaukee hospital increase when local sewers overflowed.

The problem with our old sewage systems is that they are capable of handling normal “loads”, but when it rains, the demand on the system exceeds capacity. With no place to inventory the excess water, it is spilled into local waterways.

So what is the solution when peak demand exceeds capacity? The knee jerk reaction is to increase capacity. But this can be foolish – it can be very costly to increase capacity when it will be used only at peak demand times. A better strategy is to smooth out the demand peak.  Of course, we can’t control rain, so that won’t work. But we can slow down the flow of rain into the sewage system by how we design our cities. In particular, planting trees helps to absorb the flow of water (maybe we can interpret this as an increase in capacity). Planting organic roofs can also slow down the flow of water – instead of rushing off the roof, it drips from the roof.  Or, if we could design sewage systems so that rain water was processed in a different system than toilet water, then the peak demand problem is solved - peak rain water can be safely spilled into the river and it would be unlikely to have a coordinated demand peak of toilet water, i.e., separate smooth demand from the variable demand. (I never did believe the stories about the problems induced when too many people flush during a Super Bowl commercial.)   

So what is the connection between sewage and holiday demand? Retailers face the peak demand problem in spades. The following graph plots sales of general merchandizers from 1992 to 2008 and clearly illustrates the annual holiday spike in demand

An interesting feature of this paper, contrary to what you hear in the press, is that the end-of-year spike is actually getting smoother. To illustrate, the following graph shows the % of annual demand that occurs in November and December:

From a peak of 25%, the fraction of annual sales occurring in November and December has been steadily declining, and now is about 21%.  Why is this? It could be that consumers want to smooth their consumption (they can’t wait for that holiday present) or it could be that retailers are encouraging this demand smoothing (via pricing). 

Another change in the data is the “back to school effect” - August’s sales relative to September’s sales has been showing a steady increase. Back-to-school is now the mini-Christmas of the year.

Buy now! Limited supplies!

Related to my post yesterday, the NY Times today has an article on retailers intentionally keeping stocking quantities low (NY Times, 11/19/09, Luxury Stores Trim Inventory and Discounts).  If the Brioni leather bomber jacket is what you need for that special someone this season, you better get to Saks fast because they have only 1 left – at a mere $5295! (And then you need to see a therapist to explore why you feel compelled to spend $5295 + taxes on an article of clothing which is not suitable for climbing Mt Everest or walking on the moon.)

The idea is simple – intentionally stock less than a “normal” amount so that you will not have too much inventory left over which needs to be discounted. Because if you have too much inventory left over, then customers may anticipate this and not plop down $5K to buy at the regular price, thereby certainly ensuring that you will have to discount.  Or, you are doing this to generate a sense of scarcity, and therefore desirability:

“What’s luxury retailing all about?” Mr Sadove said. “It’s about a scarcity of supply.”

Given that we are talking about ultra luxury products, I wonder if the scarcity argument holds water. If you are spending $5K on a jacket, then you better be sure that you will never see another person walking down 5th Avenue with that jacket on. But only people walking down 5th Avenue would be willing to spend that kind of money on a jacket (i.e., not everyone has the same probability of encountering another person with this jacket on). So unless that jacket is *unique*, it is not scarce enough.

Next, the standard approach to avoid markdowns with luxury goods is to not markdown! A $5K jacket probably has a very healthy margin (say $4,750), so if you have a few left over, then ship them back to the producer, take more time to sell them, or burn them. But whatever you do, don’t markdown the price! Having a few left over jackets that need to be sold in some other country with the label ripped out may be cheaper than stocking out when somebody wants to pay you an obscene amount (ok, I’ll stop harping about the ridiculousness of the price).

The article recognizes that the best approach is to start with a limited supply and then replenish only if necessary. This is feasible in some categories (contemporary apparel and women’s shoes) but not in others (European designers). Of course, this reminds us of Zara:

The graph above nicely illustrates the Zara strategy – start with a more reasonable price and a limited quantity, replenish if necessary, and don’t mark down all that much.  The net effect is that your total profit (light blue) can be higher.

And there is one key lesson from Zara that is missing in the discussion of Saks.  If Zara runs out of one item, they generally have another item available that is a close substitute. If you like a particular black bomber jacket at Zara, then you should buy it because (a) it will not be marked down and (b) if you wait then you will have to buy a different black jacket.  Either way, Zara gets the sale. In the NY Times article, they are suggesting that it can be better to simply stock out.  If you don’t have an adequate substitute, then that is really a costly strategy.  Being smart doesn’t mean you are willing to incur costs. Being smart is avoiding costs while maximizing revenue.

4Q is time for what’s hot and unavailable

Every 4th quarter there are stories about what is hot and hard to find. This year, it is the e-reader category, specifically Sony’s Daily Edition Reader ($399) and Barnes & Noble’s Nook ($259). (See WSJ 11/18/09 – Sony Says Some E-Reader Orders May Miss Christmas).  Sony is telling customers that they are now shipping orders on Dec 18th – a little tight to ensure being included as a stocking stuffer.

My favorite quote from the article is:

“The possibility that Sony, a huge electronics manufacturer, would be caught off guard by supply-chain issues is surprising, said Mike Serbinis, president of Shortcovers“

The presumption is that an experienced and large manufacturer should not have any trouble matching supply with demand. This simply ignores the fact that size and experience are no match for the uncertainties of the market.

Next, it is interesting that Sony is capable of quoting shipping dates:

“In October, the company told its first wave of customers that the Nook would ship Nov. 30. A second wave of customers was told it would ship Dec. 7; shipping dates of Dec. 11 and Dec. 18 were later given.”

This does demonstrate a sophisticated level of supply chain management, assuming their quotes are reasonably accurate: to be able to do this requires a significant amount of real-time information sharing across the supply chain and the skill to process that information quickly.

Finally, I can’t help but speculate on whether they intentionally kept supplies short. Suppose you think you could sell 100,000 units. If you make 75,000, they you are likely to run short. If demand turns out to be 120,000, you are really short and you get lots of free press about how hot your product is. But to make that strategy work, loosing thousands in sales has to cost you less than the free advertising. Hard to say if it is worth it.  Then again, it is entirely possible that if your new techno gadget isn’t “hot”, then it becomes “stone cold”. For example, if “natural” demand is 100,000 but you make 75,000, then actual demand turns out to be 125,000.  If “natural” demand is 100,000 but you make 100,000, then actual demand turns out to be 60,000 because who wants to buy a product that isn’t popular.

The diamond supply chain

Some retailers like to vertically integrate. For example, in clothing the two large players (Gap, Inditex/Zara) are vertically integrated into production (though not to fabric production). Other do not. For example, in athletic shoes (Nike/Adidas), the firms like to outsource production and do not reach all of the way back into the production of materials (such as cows for leather). The Internet giant, Amazon, doesn’t make the stuff it sells (I suspect it outsources production of the Kindle) and the physical world giant, Wal-Mart, also primarily sticks to retailing.

The supply chain for diamonds is special, in particular due to the existence of the “legal cartel”, De Beers. The WSJ yesterday (Diamond Industry Makeover Sends Fifth Avenue to Africa – 10/26/09) reported how Tiffany’s has invested in diamond cutting and polishing in Botswana. Why would they do this?

The technology for diamond cutting and polishing doesn’t seem to be particularly complex or proprietary (protected by patents, etc.). It isn’t a very capital-intensive step in the process(unlike mining), which is reason to get into it (i.e., it isn’t a big investment) and reason to let others get into it (there must be lots of competitors due to the low capital requirement). There doesn’t seem to be evidence of a cartel at that step in the process or substantial barriers to entry.

One theory is that controlling the diamond supply chain facilitates branding, and in particular avoiding the tarnish of “conflict diamonds” (see Blood Diamonds).  But, to quote a quote in the article:

“We really want the focus…to be on the quality of the diamond ring, not how it came to be,” said Mr. Kowalski, the CEO.

In other words, they are not investing in Botswana cutting and polishing to convince consumers that their diamonds are “clean”. In fact, they want to completely avoid the discussion of where their diamonds come from.

Hence, it must be that (i) the ROI on this investment is at least as high as opening up new stores and (ii) the ROI is high because vertical integration into this step creates efficiencies that cannot be had from buying cut and polished diamonds on the open market. (i) is plausible if they are running out of good places to put their stores, but they might not want to signal that to Wall Street. (ii) is plausible if the market is not sufficiently efficient to drive down margins.  Alas, the article doesn’t provide enough information to know if these theory holds water or not.

It isn’t your father’s PC industry anymore

My first PC was an IBM PC with an Intel 8088 microprocessor, two floppy disk drives and a whopping 64K of RAM (not 64MB or 64G, the 64,000 variety) – and it cost about $4000 in 1985 (but my father worked for IBM so we got it for the employee discount price of something like $2700). HP is currently selling a laptop through WalMart for $298 (or $148.47 in 1985 dollars, http://data.bls.gov/cgi-bin/cpicalc.pl). 

The PC industry has gone through many stages in which one firm was on top. Apple started it, then IBM took over. IBM tripped in the early 90s and Dell took over. Dell started to stumble about 5 years ago and now HP is on top as we see in the following graph reported in WSJ (HP wields its clout to undercut rivals, 9/24/09):

So how is HP able to do this. First, they are working with small margins, razor thin 4.6% margins. Next, the article gives some other clues to their strategy.

 (1) “Simplifying the specifications of the product”

i.e., reduce product variety so that contract manufacturers can have higher volumes and thereby offer lower prices. This is a standard recommendation in an OPs class.

(2) ”By getting orders in earlier, H-P could save on component and manufacturing costs, which are cheaper if they’re ordered far in advance.”

This line is intriguing. If component prices are falling, then ordering early is a disadvantage, not an advantage. This suggests several possibilities. First, component prices may not be falling rapidly and HP is better off giving suppliers a long lead time to get an advance purchase discount from them. Second, component prices are still falling but it is cheaper for HP to take on that risk than to let the suppliers take on that risk – i.e., if they take on that risk then they have to charge more, which is passed on to HP.

As I said, it isn’t your father’s PC industry anymore. What makes me think it could be entirely different in another 5 years?

Starbucks goes lean to pull out of its slump

In June Daniel Corsten pointed out to us a very nice article about Starbucks and how they are continuing to rethink their operations (WSJ, “For Starbuck’s  Baristas, It’s Back to the Grind, 6/17/09).  In some cases Starbucks had let efficiency reduce the customer’s experience, such as grinding coffee only once a day.  Now, they will grind throughout the day so that the shop is filled with the aroma of freshly ground coffee – less efficient but better for the customer.  That said, they are not backpedaling on all efficiency.  For example, they are making their coffee brewers more flexible (instead of brewing only one variety, now they will switch) and consequently customers will experience stockouts of their favorite variety less often. And they have a team of 10 people focused on bringing to their shops “lean thinking” alla the Toyota Production System. Given that labor represents 24% of revenue, even slight improvements in motion can make a significant difference.  That means looking for how the company can reduce the walking, reaching, and bending that goes into the making of a cup of java.  Classic process analysis. (WSJ, Latest Starbucks Buzzword: ‘Lean’ Japanese Technique 8/4/09).  The changes seem to be having a positive effect – they reported better than expected fiscal third quarter profits this year (WSJ, 7/22/09).  They’ll need to keep it up – McDonald’s and Dunkin Donuts also understand the importance of lean in how they make their coffee.

Production smoothing on a grand scale

It was just reported that the US GDP fell at an annual rate of 3.8% in the fourth quarter of 2008 but it would have fallen 5.1% had it not been for the inventory adjustment – demand “fell off the cliff” but firms kept producing, thereby causing inventories to rise.  One might interpret this as a nice demonstration of the production smoothing strategy on a grand scale – it is costly to shut down production, so keep producing and build inventory with the assumption that eventually demand will exceed your production and you can then draw down your inventory.  Production smoothing is particularly effective for coping with seasonal demand because then the firm has a good sense that demand will indeed return during the high season.  Now it is a little bit different. The drop in demand is not seasonal but systematic and it is not clear when demand will level off or at what level it will converge to. In particular, if the economy is still producing above the new long term rate of demand, then further adjustments to production will be needed.

The depth of the downturn may hinge on firms’ willingness to hold inventory. If they want to reduce their current inventories to their levels over the past five years, then they will need to really slam on the break (in effect, we have already produced for future demand and to return to equilibrium requires stopping production so that demand can catch up).  However, if firms are willing to hold on to their additional inventories, then the adjustment need not be so severe – in that case all that is necessary is that the firms align their current production with their current demand rate.

These issues are exhibited on a more “micro” scale at Chrysler. They stopped production in December 2008 because their inventories were higher than they could manage (or wanted) and continuing to produce would have only increased them further. They only just resumed production. If their current production rate equals their current demand rate, then their inventory level will remain unchanged. If they want to reduce their inventories, then they will have to produce at a rate that is lower than demand for some time.

So this raises the question of whether inventories are stabilizing or destabilizing to an economy.  You can tell a story for either one, and some additional data collection is needed to resolve the conflict.

Wall Street Journal, Jan 31, 2009, Economy Dives as Goods Pile Up

Little’s Law everywhere – even in the “body of Christ”

Little’s Law dictates the relationship between three performance metrics in a process, Inventory, Flow Rate and Flow Time:

Inventory = Flow Rate x Flow Time

If you know two of them, then you can calculate the third. It is hard to not be a Little’s Law junkie – seeing the application of Little’s Law everywhere.  Here is an application that you might not expect – the production of communion wafers. The New York Times published an article about a company in Rhode Island that makes a lot of communion wafers – about 1 billion per year. It comes with a short audio slide show which is reasonably interesting.

So what is the Little’s Law question from the article? Wafers are produced at the rate of 100 per second. They spend 15 minutes in a cooling tube. How many wafers does the cooling tube hold on average? Use Little’s Law! Inventory = 100 x 15 x 60 = 90,000, or enough for 360 Sundays at a medium sized church that serves 250 per service. (360 Sundays is almost 7 years.)

If Little’s Law isn’t your thing, then you can calculate out their process utilization. At 100 wafers per second, that is 100 x 60 x 60 x 24 x 365 = 3.2 billion wafers per year.  They only sell about 1 billion per year, so their process utilization is about 1 b / 3.2 b  = 31%

New York Times, December 24, 2008: http://www.nytimes.com/2008/12/25/business/smallbusiness/25sbiz.html?pagewanted=2&partner=rss

Out of stock for Christmas

Believe it or not, there is actually a product out of stock this Holiday season – Amazon’s Kindle. Oprah announced that she loves her Kindle and sales have exceeded Amazon’s expectations. The forecast is that they will not be in stock until February.  The key question is how many unit sales will they lose because they are not available in the peak month of the year? Probably more than they want. Even if those sales are deferred to the next holiday season, it is a costly situation for the company.  Of course, there is no way to know if they are just the victim of bad luck (or too much good luck) or bad planning, but it does illustrate that challenges of meeting highly uncertain demand.

Wall Street Journal Dec 4, 2008 – Better Scratch That Kindle Off Your List

Aldi’s operational simplicity

Aldi, the German founded grocery chain,  is a fascinating retail concept.  Like the wholesale club stores (e.g., Costcos) they sell a limited number of different items within each category.  Unlike the wholesale club store, and like a convenience store, they sell through a small physical layout.  Consequently, not only do they have limited variety within each category, they have limited overall variety – a typical grocery store carries 45,000 different items whereas an Aldi carries about 1,300 different items.  And unlike grocery stores, Aldi prides itself on its no-frills approach to service - you have to bag your own groceries, you can’t pay with a credit card or check, items are displayed in the boxes they were shipped in, most items are private label and you have to rent a grocery cart.  So why are people shopping at Aldi – in a word, “price”. Aldi claims “its private-label products were 16 percent to 24 percent below those at discounters and big-box stores, and 40 percent less than those at traditional supermarkets.”  This strategy is very much akin to Southwest’s initial approach in the airline industry – offer a very specific service to customers, with absolutely no additional service, and charge them a noticeably lower price.  It can be argued that Southwest has drifted away from that strategy.  In the current economic climate, Aldi may have extra reason to stick to its approach.

Wall Street Journal, Sep 7, 2008 – The Allure of Plain Vanilla