Limit of Detection

line chart takes the X-axis as simple serial/sequential numbers (does not reflect the predictor range); excel allows you to simply relable the x-axis with the predictor values.

on the other hand, scatter plot, actually plots the actual values of predictors vs responses. and the trend line accounts for the range of predictor values/ranges and true indicator of the linearity/trend line.

in one line…for linearity calculations use the scatter plot.