Surprisingly Seasonal Inventory Items: Insights from Forecasters, Planners and Replenishment Buyers

As shoppers prepare for the holidays, demand forecasters, inventory planners and replenishment buyers are hard at work anticipating what the rest of us will buy and when. Some items are obvious and easy to predict. Others take even the pros by surprise.

It’s a safe bet that grocers will sell more turkeys in the weeks before Thanksgiving than during the summer months. And you don’t need an inventory analyst to predict that sales of gift-wrapping paper will peak in the weeks before and immediately following Christmas.

Inventory planners and replenishment buyers can offer plenty examples of surprisingly seasonal items which make demand forecasting a challenge.

(For a complete list of fun and unusual seasonal items that friends, colleagues and customers have shared over the years, go here)

Back-to-school season for condoms and birth-control pills

The seasonal appeal of condoms and birth-control pills is no news to many college students and their pharmacists. Chemical mace and pepper spray also enjoy a back-to-school surge.

Collectively, these four inventory items represent three distinctly different strategies for prevention. The independent behavior of three separate but intersecting customer groups synchronizes their seasonal demand: female students, male students, and the worried parents of female students.

Suntan lotion a winter favorite in Minnesota

Forecasters also discovered the same merchandise item often has distinctly different seasonal demand in different parts of the country. Suntan lotion, for example, sells big in Florida all year. And its seasonal demand is strongest during winter months at drugstores near beaches. The population of Florida swells in the winter, and people use suntan lotion at the beach.

Yet central replenishment buyers for Eckerd Drug in Florida were surprised to see a similar winter demand pattern for suntan lotion in some of the chain’s most northern stores. Why would these drugstores sell so much suntan lotion in January, February and March? Is it to prevent sunburn for skiers and snowmobilers?

Maybe so. But no one could use enough suntan lotion on their hands and face to explain the strength of demand in some northern locations.

Detective work revealed the strongest winter demand in affluent areas. Well-heeled Yankees, the replenishment buyers learned, often stock up on suntan lotion – and also travel-sized tubes of toothpaste -- before leaving for winter trips to warmer climates.

Cat litter – not just for cats

In cold-weather regions, demand for cat little increases in both summer and winter. Strong demand for cat litter seems to make sense during the coldest months when cats are likely to spend more time indoors. But why do cat-litter sales also rise during summer?

The answer is simple. Some demand for cat litter has nothing to do with cats. Do-it-yourself mechanics use the product to absorb motor oil spilled on pavement. Some people also use cat litter to harden leftover paint before dumping the cans in landfills. And some people use the grit for traction on snow and ice.

The “golden age of discovery” for surprisingly seasonal items began in the early 1990s. That’s when statistical demand-forecasting systems first improved to the point of spotting seasonal demand automatically.

Different seasonal demand in different parts of town

In another example of segmented seasonal demand, mid-winter sales of “resort wear” are likely to be stronger at higher-end department stores such as Nordstrom, Bloomingdales, Saks and Neiman Marcus than at lower-priced retailers like Dressbarn, Ross Dress for Less and Stein Mart.

A window into society

Such seasonal demand patterns can be interesting beyond a small circle of forecasting geeks, replenishment buyers and statisticians. Data on the way we buy can provide fresh insights into the way we collectively live, work and relax.

You can also get surprising insight into the way people think by studying changes in the volume of Google searches on various keyword phrases over time.

Despite a long and divisive political election, we collectively behave like the occupants of an ant colony or beehive – at least in our buying and consumption of mundane items.

Demand data, in the hands of curious people, can deepen our understanding and appreciation of the wonderful richness, complexity and variety of our economy and our society.

For more examples of surprisingly seasonal items that friends and colleagues have identified over the years, please see the tables provided here.