The test consists of observing whether a small increase in price (in the range of 5 to 10 percent) would provoke a significant number of consumers to switch to another product (in fact, substitute product). In other words, it is designed to analyse whether that increase in price would be profitable or if, instead, it would just induce substitution, making it unprofitable. In general, one uses databases from the firms which may include data on variables such as
costs, prices,
revenue or sales and over a sufficiently long period (generally over at least two years). In economic terms, what the SSNIP test does is to calculate the
residual elasticity of demand of the firm. That is, how a change in prices by the firm affects its own
demand.
First phase As an example, let's suppose the following situation for a firm: •
Price = 10 •
Sales = 1000 •
Variable cost per unit = 5 In this case, the firm would make profits equal to 5000: \mathrm{Price} \times \mathrm{Sales} - \mathrm{Variable\ cost} \times \mathrm{Sales}. Now suppose the firm decides to increase its price by a 10 percent, which would imply that the new price would be 11 (10 percent increase). Suppose that the new situation facing the firm is therefore: •
Price = 11 •
Sales = 800 •
Variable cost per unit = 5 In this case, the firm would make profits equal to 4800: \mathrm{Price} \times \mathrm{Sales} - \mathrm{Variable\ cost} \times \mathrm{Sales}. As can be seen, such an increase in prices would induce a certain substitution for our hypothetical firm, in fact, 200 units less will be sold. This may be so because some consumers have started to buy a substitute product, the same consumers have bought a smaller quantity of the product given its price increase or maybe because they have stopped buying that type of product. If we want to know whether such price increase has been profitable, we should solve the following equation: \mathrm{Profits} = \mathrm{Price} \times \mathrm{Sales} - \mathrm{Variable\ cost\ per\ unit} \times \mathrm{Sales} = 4800. In our example, the increase in price produces too much consumer substitution which is not compensated by the increase in price nor the reduction in costs. Overall, the firm would make less profits (4800 compared to 5000). In other words, there are other substitute products that should be included in the relevant market and the product of the firm does not constitute by itself a separate relevant market. The "market" formed by this only product is not "worth monopolising" as an increase in prices would not be profitable. The investigation should continue by including new products which we may guess are substitutes of the one under investigation.
Second phase We already know that the previous product is not by itself a relevant market because there do exist other substitute products. Let's suppose that the previous firm (A) tells us that it considers as competitors the products of B and C. In this case, in the second phase we should include these products to our analysis and repeat the exercise. The situation can be described as follows: Given that we want to know if products A, B and C constitute a relevant market, the exercise would consist in supposing that an hypothetical monopolist X would control all three products. In that case, the monopolist would make profits of: 10 \times 1000 - 5 \times 1000 + 13 \times 800 - 4 \times 800 + 9 \times 1100 - 4 \times 1100 = 17700 Now suppose that monopolist X decides to increase the price of product A, maintaining the price of B and C constant. Suppose that a 10 percent increase in the price of A provokes the following situation: This means that the price increase of A would provoke that 200 units less of A be sold and instead, 100 more units of B and C will be sold respectively. Given that our hypothetical monopolist controls all three products, its profits will be: 11 \times 800 - 5 \times 800 + 13 \times 900 - 4 \times 900 + 9 \times 1200 - 4 \times 1200 = 18900 As can be seen, the monopolist controlling A, B and C would profitably increase the price of A by 10 percent, in other words, these three products do constitute a market "worth monopolising" and therefore constitutes a relevant market. This result is because X controls all three products which are the only substitutes of A. Thus, X knows that even if its increase in price of A will generate some substitution, a significant share of these consumers will end up buying other products which he controls, therefore overall, his profits will not be reduced but rather increased. If we had found that such an increase would not have been profitable, we should further include new products which we may imagine are substitutes in a third phase until we arrive at a situation in which such an increase in price would have been profitable, indicating that those products do constitute a relevant market. ==Limitations==