If price elasticity of demand showed how demand responds to a change in different economic conditions, Price Elasticity of Supply shows the responsiveness of the quantity supplied to a change in the price of product. As firms are usually aimed to make a profit, this relationship will be always positive, because as price for a product increase,more suppliers are willing to sell their goods and so supply will increase. In the short run, PES is usually inelastic as suppliers can't react to changes in the market so fast, but in the long run supply will decrease as prices fall.             Factors that affect PES may be increases in costs of production such as rise in the prices of raw materials, or introducing by trade partners import controls and so it will be more expensive for firms to buy materials from abroad, or rise in wages which are also costs of production. With rise in prices, PES will be more elastic, because supply will also increase.