Back to Know that straight lines are widely used to model relationships between two quantitative variables — Problem 2 · Task Set 82

Fitting Lines to Data -- Tutor Intake Assessment

This is a quick check on line-fitting concepts: when a line makes sense,
how to judge whether it fits well, and how to use a fitted line to
predict values and write its equation. The goal is to see where to focus
our first sessions together, not to grade you. Work independently,
without notes.

Grade 8·8 problems·~12 min·Common Core Math - Grade 8·container·8-sp-a-2

Work through problems with immediate feedback

Concepts

A tutor draws a straight line through a scatter plot of
study-hours versus test scores. The line does not pass through
most of the individual data points. A student says, "That can't
be a good line -- it's not even touching most of the points!"
What is the best response to the student?

The student is right -- a good line should pass through as many data points as possible

The line is a model that summarizes the overall trend; it is not expected to pass through most individual points, only to follow the general pattern and sit in the balance of the data

The line is wrong and should be redrawn to touch more points, even if that makes it less balanced

The line only needs to touch the highest and lowest data points