The supermarket dance: food for thought


Entering into Alcampo supermarket (Madrid)

When you think about it, shopping for food is one of the most important things you do. It’s related to many facets of our lives, starting with how we spend out salary, our personal health, daily planning and what and how we eat with family and friends. According to a recent survey, the average person in America spends about 8% of their salary (around $330) on food every month, while it’s about 5 % higher in Europe (Spain around 13%, see here for an illustrative graph). From the data over the past three months, I calculated that I spend about 16% of my salary on food, just for groceries (not including restaurants, etc). That’s probably a bit higher than average since we have a fairly large family and we started buying more organic foods in 2014 after my wife got pregnant.

I didn’t want to write a blog about the economics of grocery shopping, I was more interested in finding out how much “passive” data I actually have about my visits to the supermarket (data I didn’t realize I was collecting) and what it can tell me. I was curious about how frequently I bought food, what I bought most and how long each trip lasted. I also thought I could learn something from looking at the narrative photos of each supermarket visit.

Just based on my credit card data, I can see that I make around 50 visits to the supermarket every year, about once a week. Looking at it in a bit more detail, I transcribed all my supermarket receipts from this year so far, into Excel. I just looked at our visits to the main supermarket we use (Alcampo). There were a total of eight receipts, with a total of 189 items bought. The most frequently purchased items were fruit, fish, eggs, bread, yoghurt, meat and veggies. Based on the data in my notebooks and from looking at the narrative photos from each visit, I calculated that the average length of each visit was approximately 30 minutes (from entering the supermarket to after paying).

Taxes and purchase order

I noticed, I must say for the first time, while transcribing the name and price of each food item, that each price had a letter next to it referring to its tax bracket; A for 21% tax (general), B for 10% tax (reduced) and C is 4% tax (super-reduced). Foods like bread, eggs, milk, cheese, fruits, veggies and grains all fall within the super-reduced bracket.


Example receipt from supermarket with tax brackets beside price

Narrative camera

From the sequence of photos on each visit I could verify in what sequence I bought food. For example, first soap and toothpaste, then fish, meat, vegetables, fruits and the rest. So, on my spreadsheet I had all the items bought, their price and tax bracket, to which I added information from the narrative camera that told me the order in which I bought the items.

It became obvious that all the more expensive items (21% tax) were being placed near the entry to the supermarket, and taxes decreased as you went “deeper into the cave”. This is kind of similar to what I’ve read from other sources, for example here, where they suggest to buy items on the outer rim of the supermarket, not venture into the middle aisles with candies and canned goods. Or to fill up your cart with vegetables and fruit first, and then continue shopping for more expensive stuff.

So after that exercise, I can now clearly see the floor plan of my supermarket in terms of the three tax brackets, the A tax zone at the beginning (cosmetics and everything from office supplies to home hardware stuff), the B tax zone (mostly fish and meat), and then C (mostly fruits and veggies).

Going organic

As I mentioned above, my family started to go more organic back in 2014, and I was also curious about how much more money I was spending on food compared to my pre-organic life. This was easy to do based on my bank and credit card statements, and equalled 46% increase per month when I compare 2012 to 2015. However, it was harder to verify that the data was very real, since in 2012 I went more often to our local farmer’s market (paying cash, and often no receipt) and in 2015, more often to the supermarket (credit and receipt). An argument can probably be made that when you go organic, you probably end up buying less food in general, so the price increase may be less than 46%.

Last week I was reminded about my “organic spending” when I was asked to fill in a questionnaire about how I bought food and how much more I was willing to pay for food items that were free of antibiotics and pesticides. I answered that I would be willing to pay 50% more for organic fish and meat and 30% more for vegetables and fruit. Going to the data however, we often pay double, so more like 100% for organic, especially for fruits and vegetables, and then about 50% more for organic meat. There are very few options for buying organic fish and the price hike is more like 300%.

Food for thought.



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