[This is one of a series of posts that explore real world examples of mathematical modeling to help educators better understand its applications. This is not intended to be a context for a student lesson. To learn about Spies and Analysts, I recommend watching this webinar (with elementary, middle, and high school versions) or reading this blog post.]
You’ve probably heard of dating websites (like eHarmony, OkCupid, or Match.com) that help you find someone you might be interested in. You enter your information, take a survey, and then hope you’re connected with the right people. That’s what the websites hope too, because they make their money through people signing up for memberships. The reality for these websites is that people have to see others they are interested. If they do, they will stick around, refer their friends, and the company will make money. If not, their customers will leave and they will go out of business.

So, what if you worked for eHarmony and they asked you to create a formula to decide which people to pair up? Where would you begin? What information would you want to know? What would you do with that data once you had access to it? These are the topics I’m exploring in my spies and analysts post. I want to walk you through the process so that you can better appreciate the complexities of mathematical modeling.

The first part of the process requires the spies. So, I want you to stop and take thirty seconds to think about what information you would use to match potential customers. Would you look at where they lived? How old they were? How much education they have? The kinds of foods they like to eat? Whether they want to get married? The list of questions could go on and on. So, think about what information you’d pick if this was your job. Once you’ve determined what information you’d want, keep reading.

I hope you’re starting to get a sense of the enormous number of factors to consider. You have to balance the reality that you need to ask many questions to learn about your customers’ preferences, but you also don’t want to overwhelm them with a survey that takes hours to complete. Choosing the right questions is not easy, and that is part of why some dating website succeed while others fail.

As for eHarmony, they are so proud of what they ask you about that they advertise their “29 dimensions of compatibility” as a selling point for their website. Those dimensions are:

Character & Constitution:
  • Good Character
  • Dominance vs. Submissiveness
  • Curiosity
  • Industry
  • Vitality & Security
  • Intellect
  • Appearance
  • Sexual Passion
  • Artistic Passion
  • Adaptability


Emotional Makeup & Skills:
  • Emotional Health
  • Anger Management
  • Quality of Self Conception
  • Mood Management
  • Communication
  • Conflict Resolution
  • Kindness
  • Autonomy vs. Closeness


  • Obstreperousness
  • Sense of Humor
  • Sociability
  • Energy
  • Ambition


Family & Values:
  • Feelings about Children
  • Family Background
  • Education
  • Spirituality
  • Traditionalism
  • Values Orientation

In reading this list, many definitely make sense. Some, like “Obstreperousness” I had never even heard of. So, let’s imagine that you made a survey that measured all of these factors. Now what? How do you turn them into a person to show? Is “Education” more important than “Ambition”? What about the reality that what people say they want often differs from the people the date? This is where the analysts come in. Their job is to take the data, figure out what parts are more or less important, and break it down in such a way that it becomes useful. Take 30 more seconds to think about how you might even begin to work with the data.


Having so much information is both a blessing and a curse. What would you do with all that information? I think that most people would begin by looking at what is most important. However, what’s really interesting about this process is that the answer is both what information should be prioritized and what information should be ignored. Here’s what Dr. Steve Carter, the Chief Scientist at eHarmony said:

The Chief Scientist at eHarmony has revealed that although singles are asked to choose likes and dislikes on a sliding scale, unless they pick the extreme ends their answers will be largely ignored. Dr Steve Carter said it stopped daters ending up ‘in a universe of one.’

Think about that! Sometimes to make customers happy, they have to be saved from themselves by ignoring what they say!


I’m hoping that at this point, you have a better appreciation for the complexities of mathematical modeling. Once the spies and analysts are done acquiring the information and putting it together, they still have to determine whether the formula (or mathematical model) they come up with is any good. For example, if people aren’t finding many matches that turn into relationships, it could be a sign that your mathematical model is not doing its job. Can you imagine the never-ending refinement that a model like this must require?

At this point, there are no computers or calculators that can figure this out on their own. This is where the jobs are at. If we truly want to focus our time and energy in a skill that will really help our students become college and career ready, mathematical modeling is where we need to be.


  1. WOW Here’s a great answer to ” WHy do I have to know this?” Love the real world connecton I can now make with my students- to be able to model at that level you need to get a good foundation here in elementary school!

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