2. Know that straight lines are widely used to model relationships between two quantitative variables. For scatter plots that suggest a linear association, informally fit a straight line, and informally assess the model fit by judging the closeness of the data points to the line.
NBA top 100 (points per game vs. shots per game)
High School Dropout Rates vs. Teen Pregnancy Rates
Crime Rates vs. Unemployment Rates
*Source: Bureau of Labor Statistics, City-Data.com