The "concept of elasticity of demand" measures the relationship between a change in the price of a product and the corresponding change in the quantity demanded of that product. The elasticity of demand may be perfectly elastic, perfectly inelastic or somewhere between the two.
Elasticity of demand is found by dividing the percentage of the change in quantity by the percentage of the change in price. If the quotient is zero, demand is perfectly inelastic, which means that a change in price yields no change in the quantity demanded. If the quotient is one, demand is perfectly elastic, which means that a change in price yields an equivalent change in quantity demanded. Most goods fall somewhere between perfectly inelastic and perfectly elastic. Businesses use demand elasticity to predict the effect of price on product sales.
Elasticity of demand is determined by several factors, including the availability of substitute products, the cost of switching between products, and whether the product is a necessity or a luxury. Products that have readily available substitutes tend to be more elastic than goods with few substitutes. Necessities tend to be more inelastic than luxuries. Products with highswitching costs are more inelastic than goods with lowerswitching costs.
The degree of responsiveness of change in demand as a result of change in its price is known as elasticity of demand. I mathematical language we can say that; Elasticity of demand
http://wiki.answers.com/Q/What_is_meant_by_concept...

A measure of the relationship between a change in income and a change in quantity of a good demanded: Investopedia Says: The degree to which a demand for a good changes with respect
http://www.answers.com/topic/incomeelasticityof...

Income elasticity of demand measures the responsiveness of the quantity
http://www.chacha.com/question/whatistheincome...

If people have more money to spend (they get hired at a new job or get a raise at their current job) they will buy more things. That means that they buy (demand) more things. The
http://answers.yahoo.com/question/index?qid=201305...
