https://community.jmp.com/t5/Discussions/Lack-of-fit-test/m-p/947094#M109726 <P>Hello everyone. I have a question related to DOE.<BR />When conducting a Lack of fit test, how should the F ratio be calculated? F=MS residual /MS pure eror&nbsp; or&nbsp;</P> <P>F=MS lack of fit/MS pure eror. The idea is to compare the model error with the experimental error..&nbsp;</P> <P>Are the results obtained from the two formulas different? Which result is more reliable and when is it necessary to use each of the two formulas?</P> <P>The first formula gives a lower value of f compared to the second formula for the same data.</P> <P>I would be grateful if someone could clarify this issue.</P> <P>Best regards, Milen</P> Sun, 10 May 2026 09:36:10 GMT DiscreteIbex427 2026-05-10T09:36:10Z https://community.jmp.com/t5/Discussions/Lack-of-fit-test/m-p/947094#M109726 <P>Hello everyone. I have a question related to DOE.<BR />When conducting a Lack of fit test, how should the F ratio be calculated? F=MS residual /MS pure eror&nbsp; or&nbsp;</P> <P>F=MS lack of fit/MS pure eror. The idea is to compare the model error with the experimental error..&nbsp;</P> <P>Are the results obtained from the two formulas different? Which result is more reliable and when is it necessary to use each of the two formulas?</P> <P>The first formula gives a lower value of f compared to the second formula for the same data.</P> <P>I would be grateful if someone could clarify this issue.</P> <P>Best regards, Milen</P> Sun, 10 May 2026 09:36:10 GMT https://community.jmp.com/t5/Discussions/Lack-of-fit-test/m-p/947094#M109726 DiscreteIbex427 2026-05-10T09:36:10Z