We sometimes like to think of breaking habits in terms of how little effect one transgression will have on the big picture. "It's just one slice of pizza," you might argue, or "It's just one day off from the gym." No big deal.
And in a way, you're right. One day isn't really a big deal when you compare it to the other 364 days in a year.
Or is it?
How to answer the question
These kinds of questions can be hard to answer empirically because so many variables are involved. But, funnily enough, bad weather can provide a kind of external mechanism that makes it possible. In an ingenious study, public policy professor Joshua Goodman of the Harvard Kennedy School of Government found that there's a stark difference in the impact of school absences versus school closures.
The negative effects of snow
Goodman found that more kids stay home from school when the weather is bad, but that all kids miss class when the weather is really bad and schools close. That's fairly obvious, but few have taken the time to separate out possible differences in the effects of each situation.
Goodman determined that school closures don't affect student outcomes (defined in this case as standardized test performance). On the other hand, individual student absences do have an impact -- especially when it comes to math achievement.
The power of the individual
How can this be?
It's probably because when schools close, teachers can easily reschedule their lesson plans for the whole class, so it's a case of no harm, no foul. But when one individual misses a class -- particularly math, where lessons are cumulative -- both that student and his or her classmates are affected by the disruption. With students missing school at different times, coordinating where everyone is on the syllabus becomes more challenging, and thus performance declines.
Goodman found that these types of disruptions can have a significant impact on math performance, and that it can explain up to 25% of the income achievement gap: Poorer kids tend to miss more school.
What does this have to do with me?
There is also research indicating that partners in a relationship can influence each other's habits (for good or bad), meaning that one person falling off the exercise wagon, for example, can encourage the other to do the same.
With that in mind, I'd venture to guess that the downsides of missing one day don't just apply to school. In the adult version, think about your colleagues or clients, who might be waiting for something from you in order to do their jobs. What about the effects on your family when you don't tackle that retirement savings program, or when you stop eating healthfully?
So the next time your kid wants to stay home on a snowy day to watch movies, or you feel like splurging your savings on something frivolous, consider the lesson of the snow day: What you decide can not only affect your own life, but those of others. Is it worth the splurge?