Hill model fits to simulated data. In the first three columns K = (0.6, 0.6, 0.6, 0.6) was held fixed and the spread of k values was increased to simulate greater degrees of k negative (top row) and positive (bottom row) cooperativity. Analogously, in the 4th to 6th columns, k = (4, 4, 4, 4) was held fixed and K was varied. These simulations demonstrate that increases in k negative cooperativity map to increases in Hill positive cooperativity until a point is reached (e.g. in the 2nd column) where the fit is too poor to accept. Meanwhile, k positive cooperativity in the bottom row of columns 1 to 3 and K cooperativity in columns 4 to 6 map to Hill coefficients h in an expected manner.