THIRTY-ONE PERCENT OF California households are run by single parents, but Jess would never have guessed that from the people streaming into the Alice Birney Elementary Science-Art Fair meeting. Being a solo parent at a school event was like being a single person at a couples’ party. Minus the wine. If Nana or Pops wasn’t with her, Jess was made intensely aware that the other parents had no idea how to interact with a single mom. The longest conversation she’d had with someone there had been at the first-grade holiday recital when a mom had asked if Jess’s husband was going to be sitting in the empty seat next to her. When she’d said, “No husband, free chair,” the other woman smiled awkwardly for a few beats before rolling on breathlessly for five minutes about how sorry she was that she didn’t know any nice single men.

But for the first time at one of these events, she realized as she walked into the hall, Jess was relieved to be alone; she wouldn’t have to small-talk. She wasn’t sure she’d be able to do that tonight; every meeting she’d had today had been a dead end. Well, except the Jennings Grocery meeting. That was a complete disaster.

One of the biggest sins in statistics is cherry-picking—choosing which data sets to include in analysis after the study is finished. There are plenty of legitimate reasons to drop outliers: the data isn’t collected correctly, etc. But if a data point affects both results and assumptions, it must be included. And just as Jess suspected, Jennings Grocery didn’t just want to exclude a few data points in the set they sent her; they wanted to eliminate enormous territories entirely in their report to shareholders, because the numbers didn’t fit their projected sales targets.

She refused—even though she’d spent four months meticulously designing the analysis, writing the code, building the program. During the meeting, the executives had exchanged extended periods of silent eye contact, and eventually shooed Jess out of the room, saying they’d be in touch.

Was it stupid to be so inflexible with her biggest account? She couldn’t shake a sense of panic. If she lost Jennings, she would lose a third of her income for the year. Juno might need braces, and she’d be driving in eight years. What if she wanted to start doing dance competitions? What if she got sick? Nana and Pops weren’t getting any younger, either.

Movement in her peripheral vision pulled her attention, and Jess watched Juno’s second-grade teacher, Mrs. Klein, and the principal, Mr. Walker, come to the front of the room. Mrs. Klein was dressed as some hybrid of a scientist and artist: lab coat, goggles, beret, paint palette. Mr. Walker was dressed as, Jess supposed, a kid: baggy shorts, knee-high socks, and a Padres baseball cap. They sat in chairs facing the assembled parents.

The principal-child crossed his arms and pouted dramatically, and the room fell to a hush. “I don’t even get what a science-art fair is. Do I have to do it?”