text: The Hill coefficient is a measure of ultrasensitivity (i.e. how steep is the response curve).
  The Hill coefficient,  or , may describe cooperativity (or possibly other biochemical properties, depending on the context in which the Hill equation is being used). When appropriate, the value of the Hill coefficient describes the cooperativity of ligand binding in the following way:
  *. Positively cooperative binding: Once one ligand molecule is bound to the enzyme, its affinity for other ligand molecules increases. For example, the Hill coefficient of oxygen binding to haemoglobin (an example of positive cooperativity) falls within the range of 1.7–3.2.
  *. Negatively cooperative binding: Once one ligand molecule is bound to the enzyme, its affinity for other ligand molecules decreases.
  *. Noncooperative (completely independent) binding: The affinity of the enzyme for a ligand molecule is not dependent on whether or not other ligand molecules are already bound. When n=1, we obtain a model that can be modeled by Michaelis–Menten kinetics, in which , the Michaelis–Menten constant.
  The Hill coefficient can be calculated approximately in terms of the cooperativity index of Taketa and Pogell  as follows:
  where  and  are the input values needed to produce the 10% and 90% of the maximal response, respectively.