Kinds or Types & Demand Elasticity Curve ~ Elasticity Demand measures the relative change in the number of units of a good purchased as a result of changes in one of the influencing factors (ceteris paribus).

### 1. Types of Elasticity of Demand

Elasticity of demand There are five kinds of demand, namely elastic demand, inelastic demand, unitary demand or normal demand, perfectly elastic demand and perfectly inelastic demand. For more details about this type of request, please look at the following table image:

Information:

% Qd = Percentage change in quantity demanded for goods

% Pd = Percentage change of the price of goods

From the table above, elastic demand has the formula E> 1 where this demand usually occurs in the demand for luxury goods. Inelastic demand has the formula E<1 where this demand usually occurs in the demand for basic or primary goods. Furthermore, unitary demand or normal demand with the formula E = 1 where this demand occurs in the demand for goods of secondary needs. In perfectly elastic demand has the formula E = ~ which usually occurs in the demand for world goods such as wheat and oil. The last demand is perfectly inelastic demand which usually occurs in the demand for necessities such as land and drinking water with the formula E=0.

#### a. Inelastic Demand

Inelastic demand occurs when the percentage of demand is less than the percentage change in price. In other words, a price change of X% is followed by a change in demand of less than X%. Inelastic demand is indicated by a coefficient that is less than 1 (Ed < 1).

As in the demand for corn, because Ed = 0.83 (smaller than 1) is obtained, the demand for corn is classified as inelastic demand. Goods that have an inelastic demand are basic necessities.

#### b. Unitary Request

This demand occurs when the percentage change in demand is equal to the percentage change in price. In other words, an X% change in price is followed by an X% change in demand. Unitary demand is indicated by a coefficient (Ed) which is equal to 1 (Ed = 1).

This demand occurs for a variety of goods at any given moment by chance.

#### c. Elastic Demand

Elastic demand occurs when the percentage change in demand is greater than the percentage change in price. In other words, a price change of X% is followed by a change in demand of more than X%. The demand for elasticity is indicated by a coefficient (Ed) which is greater than 1 (Ed>1). Goods whose demand is elastic are secondary and tertiary (luxury) goods and goods that have substitutes.

#### d. Perfectly Inelastic Demand

Perfectly inelastic demand occurs when the percentage change in demand is 0% while the percentage change in price is X%. In other words, even if the price changes X%, the demand remains unchanged (0%). This demand is indicated by a coefficient (Ed) which is equal to 0, obtained from Ed = = 0.

Goods whose demand is perfectly inelastic are goods that are cheap and relatively unimportant, such as coriander and pepper. From the graph of example question 4, it can be seen that no matter how much the price changes, it doesn’t affect the quantity demanded.

#### e. Perfect Elastic Demand

This demand occurs when the percentage change in demand is X% but the percentage change in price is 0% (no change). In other words, even if price does not change, demand changes by X%. This demand is indicated by a coefficient (Ed) whose magnitude is ~, obtained from Ed = = ~

Examples of goods whose demand is perfectly elastic are BBM (fuel oil), such as gasoline, kerosene, and others. From the graph it can be seen that even though the price does not change, demand can continue to change.

### 2. The curve of elasticity of demand

Elasticity Demand can be interpreted as the level of flexibility or the level of sensitivity of demand to price changes.

Elasticity Curve of Demand:

1. Elastic demand demand;
2. Demand is inelastic demand;
3. Unit request request;
4. Perfectly elastic demand demand; and
5. The demand for demand is perfectly inelastic.

#### Reference :

1. Nopirin, Introduction to Macro and Micro Economics, BPFE, UGM, Yogyakarta, 2000
2. Sukirno, S, 2011, “Introduction to Microeconomic Theory”, PT Raja Grafindo Persada, Third Edition, 26th Edition, Jakarta.
3. http://myilmu Lintas Hukum.blogspot.co.id/2015/12/pengertian-dan-factor-penentu.html
4. http://myilmu Lintas Hukum.blogspot.co.id/2015/12/teori-permintaan.html
5. http://myilmu Lintas Hukum.blogspot.co.id/2015/12/pengertian-elastisitas.html

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