Very High R square and significant lack of fit problem
Hi,I made custom design for 7 factors with a model containing main effects, interractions and 2 order powers. Number of sample size is 150. I see that 3 of factors are important and made model for these 3 variables.However i faced with significant lack of fit problem and 0.99 R^2 value.I searched a lot about the reasons of this situation but i could not find a clear answer.Do you have an idea abou...