Negative Demand: A product is said to face negative demand when a significant segment of the market dislikes it and even pays to avoid it (Kotler and Keller, 2006, p. 10). The fundamental task of marketing managers in this situation is to find out the reasons for this negative demand state to the product and take effective measures to counteract them (Sandhusen, 2000, p. 59). People in some countries have a negative demand for vaccination, but, it is very unlikely in the demand for bifocal lenses.
No Demand (Nonexistent demand): When the target-market customers are unaware or are uninterested in a product, it is called no demand state (Kotler and Keller, 2006, p. 10). The main task of marketing managers in this state will be to connect potential product benefits to the needs and wants of the target-customers. This is also very unlikely in the case of demand for bifocal lenses, because, people are well aware of it.
Latent Demand: It is when many prospective consumers share a strong need but that cannot be satisfied by the existing product (Kotler and Keller, 2006, p. 10). For example, demand for hair restoratives and painless diets (Sandhusen, 2000, p. 59). The marketing manager is, in this state, expected to measure the potential demand and develop products accordingly. Currently, sufficient quantities of bifocal lenses are available in the market to satisfy prospective demands for it. Latent demand is often described as a vague want (Baker, 1998, p. 80).
Declining Demand: It is a state in which customers begin to buy a product less frequently or not at all (Kotler and Keller, 2006, p. 10). Even though demand for bifocal lenses is not declining, some factors can likely cause it in the future. In this case, the marketing management is responsible to analyze reasons and project better strategies to counteract the trend.