<p>The calculator will always calculate a regression line for you but it is meaningless if the data is not linear. Do you just eyeball the data to see if its linear or is there a set of conditions or formula to tell if it is linear?</p>
<p>first, you have to look at the scatter plot for the straight enough condition. then you have to also look at the residual plot to make sure there is no pattern. then make sure r , or the correlation coefficient is high enough as well. and then you should be good!</p>
<p>“Do you just eyeball the data to see if its linear”</p>
<p>Pretty much. And make sure the residuals are random.
All the plots I’ve ever see in AP Stats with any correlation at all were obviously linear-looking or could be made linear by doing something to one of the variables.</p>