The Price of a Free Salad

The Price of a Free Salad
By Anonymous | June 18, 2021

How do you celebrate your birthday? If you’re anything like me, you prioritize friends, family, and cake, but you let some of your favorite corporations in on the mix, too. Each year, I check my email on my birthday to find myself fêted by brands like American Eagle, Nintendo, and even KLM. Their emails come in like clockwork, bearing coupon codes and product samples for birthday gifts. 

An image of multiple emails and their contents that offer birthday discounts
Birthday email promotions

Most of these emails linger unopened in my promotions tab, but my best friend makes an annual odyssey of redeeming her offers. One year I spent the day with her as we did a birthday coupon crawl, stopping by Target for a shopping spree and a free Starbucks coffee, Sephora for some fun makeup samples, and ending with complimentary nachos at a trendy Mexican restaurant downtown.

I used to want to be savvy like her and make the most of these deals, but lately, I’ve been feeling better about missing out. The work of Dr. Latanya Sweeney, a pioneering researcher in the field of data privacy has taught me what powerful information my birthday is. 

In her paper “Simple Demographics Often Identify People Uniquely”, Sweeney summarizes experiments that showed that combinations of seemingly benign personal details, such as birthday, gender, and zip code, often provide enough information to identify a single person. She and her team even developed this tool to demonstrate this fact. 

Sample uniqueness results
Sample results from the uniqueness tool

I keep trying this website out with friends and family, and I have yet to find anyone who isn’t singled out by the combination of their birthday, gender, and zip code. 

But what does this mean for our beloved birthday deals? Let’s think a bit about how this would work if you were shopping at, say, Target. You don’t have to shop at Target very often to see promotions of its 5% birthday shopping deal. 

Target circle birthday discount
Target circle birthday discount

Attentive readers may be wondering: “If Target knows who I am already, why do I care if they can identify me with my birthday?” This is a fair question. The truth is that, in our online, tech-enabled world, even brick and mortar shopping is no longer a simple cash-for-products exchange.

Target and other retailers are hungry to know more about you so that they can sell you more products. There are a lot of different ways that companies get information about you, but most fall into three main categories. 

1. They ask you questions that you choose to answer. 

2. They track your behavior online via your IP address, cookies, and other methods. 

3. They get data about you from other sources and match it up with the records that they have been keeping on you.

This last method makes your birthday tantalizing to retailers. Target already has access to data about you that is incomplete or anonymized, whether that’s from your online shopping habits or by tracking your credit card purchases in stores. Your birthday may just be the missing link that helps it get even closer to a full picture of who you are, which it will use to motivate you to spend more money.

Data exchange works both ways, so Target may decide to monetize that detailed profile that it has of you and your behavior with other companies. In fact, Target’s privacy policy says that it might do just that: “We may share non-identifiable or aggregate information with third parties for lawful purposes.” 

The more Target knows about you, the easier it would be for another company to identify you within a “non-identifiable” dataset. Even if companies like Target are diligent about removing birthdates from databases before sharing them, they are vulnerable to security breaches. Birthdays are often used by websites to verify identities. If your birthday is part of the information included in a security breach, that increases the odds that you will be targeted for identify theft and fraud.

After I started writing this post, I found an email from Sweetgreen that reminded me that somehow, despite years of using their app regularly, I still haven’t given up my birthday.

A Sweetgreen marketing email promising a discounted salad in exchange for my birthday.
A Sweetgreen marketing email promising a discounted salad in exchange for my birthday.

I’ve always loved a good deal, and I have a soft spot for $16 salads. I wonder, if I’m already being tracked, if my activity is being monitored, if my history is fragmented into databases and data leaks, why not get some joy out of it? Why not share free nachos with friends and pile a Sweetgreen salad with subsidized avocado and goat cheese? 

Ultimately, I still can’t justify it. My privacy and security is not for sale. At the very least, it’s worth much more than $10.