## Factorising a quadratic?

well, I don't need any measurements below 107 steps!!!

I will look into using a linear model...

thanks for your help
 Recognitions: Homework Help The ordered pairs shown in your FinalCurve_Obj.jpg image attachment can be plotted onto a cartesian coordinate system, and a best line can be drawn. Any points on the line can be used for finding slope, and several points can be used for finding a y-intercept, an average of these taken, and then this can be used as the best y-intercept. I tried this and found a line to fit as y=(114/63)x-188 Similar to what you said, near x=148 and x=158, the resulting y deviates about 3 inches from what you expected. Much of the rest of the line is a very good fit.
 Mentor Careful with mixing relative and absolute error, the value for 112 steps has a larger relative error. I agree that 2-3 inch are a reasonable value for a maximal error (not including possible measurement uncertainties), but the relative error can be large for small values in column L.