In the equation, the early, unimpeded growth rate is modeled by the first term formula_52. The value of the rate formula_50 represents the proportional increase of the population formula_46 in one unit of time. Later, as the population grows, the modulus of the second term (which multiplied out is formula_55) becomes almost as large as the first, as some members of the population formula_46 interfere with each other by competing for some critical resource, such as food or living space. This antagonistic effect is called the "bottleneck", and is modeled by the value of the parameter formula_51. The competition diminishes the combined growth rate, until the value of formula_46 ceases to grow (this is called "maturity" of the population).