what is a polynomial of the first degree is variability always constant a function of model function does the model function include a polynomial? what term is missing in the model function when fitting a frequency domain model? residuals are non constant what term is missing from a residuals model which term is missing in the model function? what is the difference between a variable and a variable with an incomplete residual? what is the missing term in the model function? what kind of residuals are in frequency domain can you find the variable residual what is residuals what is non constant standard deviation why is variability constant in residuals which residual is the missing term in the model function is polynomial of the first degree residuals constant what is the missing term from the model function of variance? what is non constant standard deviation in residuals which residual term has a non constant standard deviation what residuals are non-constant