The addition of random coefficients allowedthe slope and intercept of the green life response to the fixedeffect of ethylene concentration to vary with growing districtand time of purchase. The general form of the equation was:y = a + b * x + c * x2+ d * z + e * x * z + district * time + district * time * xwhere y = green life (days), x = log10ethylene concentration (L/L)and z = storage temperature (◦C). Random terms are italicised.