Items such as everyday foods and beverages like most basic necessities tend to be PED inelastic.  By contrast, products such as designer clothing and restaurant meals are considered luxury items and are normally PED elastic.

If a good or service has a number of close substitutes then demand will normally be price elastic as consumers can easily switch their consumption to substitute products, when prices rise.  A good which is unique and has relatively few substitutes will normally be PED inelastic.

The more compliments that a product has the less PED elastic the good or service is likely to be.  For example, petrol is PED inelastic because it is a necessity product for those people who have cars.

Products which have strong consumer brand loyalty tend to relatively inelastic demand - consumers are prepared to accept price increases because of other attractive features of the brand which mean they will stay loyal. Conversely, a product with little or no brand loyalty will find demand is elastic - consumers are prepared to quickly switch to an alternative if the price increases.

There may be significant costs involved in switching between products. In this case, demand tends to be relatively inelastic. For example, mobile phone service providers may insist on 12 or 18-month contracts being taken out.  Some gym memberships require a 3-6 month notice period for cancellation.

Goods and services that consume a substantial proportion of a household’s income will tend to be more PED elastic than products where large price changes makes little or no difference to someone’s ability to purchase the product.  Higher priced items are also more likely to fall into the luxury category than low priced items.

Demand tends to be more price elastic, the longer that we allow consumers to respond to a price change.

When consumers purchase the good or service on a frequent and habitual basis, the consumer becomes less sensitive to the price of the good because they continue to buy the same products at regular intervals, without noticing small changes in price.

inelastic, elastic

This is difficult to decide whether the good is PED elastic (due to its high number of substitutes) or inelastic as a result of bread being a basic necessity.  The two factors may even cancel each other out making the product unitary elasticity. 

The demand for petrol will be influenced by the long term price of cars (a complimentary good), the availability and reliability of public transport (a substitute good) and factors such as income, the volume of traffic and the availability of parking spaces.

Items with low price elasticity of demand:
 

Pediatric visits − 0.03

Car fuel − 0.09

Eggs − 0.1

Tobacco − 0.15

Bus travel − 0.2

Steel purchases - 0.2

Samsung LCD TV - 0.9

Luxury cars - 1.4

Holidays - 1.8

While both economic concepts exist within the IB economics course, the reality is that probably neither exist in the real world.  The closest any product comes to a PED of 0 would be a highly addictive substance such as Heroine or life saving medicine.

Similarly, the closest that any product comes to perfectly elastic demand would be a highly competitive market, with a large number of firms, selling largely homogenous products such as stockbrokers dealing in the purchasing and selling of shares on a stock market.