The knowledge comes from a new feature called Zbubbles, which gives online shoppers real-time price and value comparisons.

FORBES: Window Shopping

There have been voices sceptical about the value of Pisa test comparisons and how they are used.

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The foreign currency exchange guarantees that everyone ends up with the currency they want as well as sets the standard of comparisons like the value of cars in yen to the value of food in dollars.

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Of course, these comparisons also ignore the convenience factor as well as the value of your time.

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Mobile shopping, price comparisons and internet only deals will rival doorbusters in terms of value offered and complexity.

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The company is worth more than a billion, based on comparisons to such public rivals as Parker-Hannifin and Rotork, even when its value is discounted for being privately-held.

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Councils' compliance with the best- value rule would also be checked using a beefed-up version of the Audit Commission's annual comparisons of their costs and efficiency.

ECONOMIST: Local councils