I prepared hydrogel from extracellular matrix and measured the absorbance at 405 nm during 2 hours then blotting the points in excel to calculate speed of the gelation (s) , t lag and t50%. I understand from different puplications that s refer to the slope of the linear portion of the curve. From linear regression equation y= mx+b that m is the slope =gelation speed. But I didn't understand how to calculate the other parameters from the equation or the blotted curve. Can any one explain in details how to calculate each parameter? Thank you