In late 2013, McResources, McDonald’s employee website, posted curious advice¹ to its hourly workers: it suggested the appropriate amount to tip their au pairs, pool boys, and personal trainers.

For context, the Bureau of Labor Statistics reports food preparers, such as McDonald’s employees, earn a median pay of $10.93 per hour² (see Figure 34-1); childcare workers (au pairs), $10.72;³ grounds maintenance workers (pool boys), $13.51;⁴ and fitness (personal) trainers, $18.85.⁵

A full-time, $10.93-per-hour McDonald’s worker would earn approximately $22,730 per year (2,080 hours). Assuming this worker hired an au pair to cover her full-time schedule, she would spend $22,290 per year on childcare alone. If the McDonald’s worker had her pool cleaned for an hour once a week, she might expect to pay a meager $702.52. Assuming she can make it to the gym, too, she would pay an additional $980.20 for her personal trainer. This leaves the McDonald’s worker $1,242.72 in debt annually before taxes, before all other living expenses—and before tipping. Not a lot of Happy Meals.

Clearly, McDonald’s hourly workers do not hire many au pairs, pool boys, and personal trainers. The press pilloried the company for its tone-deafness to the economic challenges of its employees . The mistake was regrettable and avoidable.

Quantitative research does not always demand an extensive research study. Sometimes, it simply requires a calculator.