Fitting a Line to Data
Aligned to 8.SP.A.2 — Common Core State Standards for Mathematics.
What this lesson teaches
Many scatter plots can be modeled with a straight trend line that runs through the middle of the points, with roughly equal numbers above and below it. The more tightly the points cluster around the line, the better the fit.
Worked example
For the points (1, 2), (2, 3), (3, 5), (4, 6), a line like y = x + 1 passes near all of them: at x = 3 it predicts 4, close to the actual 5. Because every point is within about 1 unit of the line, it is a good fit.
Practice questions
- What makes one trend line fit a set of data better than another?
- Draw a line of best fit through a set of scattered points and explain your placement.
- If most points lie far from your line, what does that tell you about the fit?
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Ajuste de una Recta a los Datos
Muchos diagramas de dispersión pueden modelarse con una recta de tendencia que pasa por el centro de los puntos, con aproximadamente la misma cantidad de puntos arriba y abajo de ella. Mientras más agrupados estén los puntos alrededor de la recta, mejor es el ajuste.
Ejemplo: Para los puntos (1, 2), (2, 3), (3, 5), (4, 6), una recta como y = x + 1 pasa cerca de todos: en x = 3 predice 4, cercano al valor real 5. Como cada punto está a menos de 1 unidad de la recta, es un buen ajuste.
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