Math & Statistics

Linear function and linear regression sound alike but they do completely different jobs. One follows a rule. The other discovers one. And once you see the difference, a lot of data science starts to make sense. A Tale of Two Lines You and your friend both work part-time at a bubble tea shop. You get paid $15 per hour. Simple. After 3 hours you know you’ve earned $45. After 6 hours, $90. There’s a perfect formula. No surprises, no guessing. ...

You and your friend both average 8,000 steps a day. Same average. Same fitness goal. But your weeks look completely different. You walk about 7,800 to 8,200 steps every day. Some days are slightly higher, some slightly lower, but you are remarkably consistent. Your friend is the opposite. One day she walks 2,000 steps. The next she finishes a half marathon and records 18,000. A few days later she barely leaves the couch with 1,500, then cycles to work and reaches 14,000. ...

Let’s Start With a Story Imagine you work at a café and earn $15 per hour. As you work more hours, the amount of money you earn grows as well. Every additional hour adds another $15 to your pay. Many situations in everyday life behave like this - when one thing changes, another changes alongside it in a steady and predictable way. This idea is at the heart of what mathematicians call a linear function. ...

A simple look at why ‘average’ doesn’t always mean what you think it means.